SCROLL NEWS / DISCOVERY
Search headlines
Find the stories shaping the conversation.
Results for " sun " 8,918 found 🔀 AI-powered Shuffle
Patriots game day roster: Player health prompts multiple changes
A look at the Patriots’ game day roster for Sunday.
Crash-and-grab burglars target NW Side business, Chicago police say
Chicago police are investigating after burglars crashed into a Northwest Side business on Sunday morning.
DIALOGUE: NAMI Albany invites community to support mental health at NAMIWalks
Ngina Mandouma and Kelly Wesselman discussed their involvement with NAMI on Sunday’s Dialogue
DIALOGUE: NAMI Albany invites community to support mental health at NAMIWalks
One in five Americans live with a mental illness. The Albany chapter of the National Alliance on Mental Illness wants to remind the community that no one has to face it alone. Ngina Mandouma and Kelly Wesselman joined Sunday’s Dialogue to discuss their involvement with NAMI and to invite the community to support mental health for all through NAMIWalks.
DIALOGUE: NAMI Albany invites community to support mental health at NAMIWalks
One in five Americans live with a mental illness. The Albany chapter of the National Alliance on Mental Illness wants to remind the community that no one has to face it alone. Ngina Mandouma and Kelly Wesselman joined Sunday’s Dialogue to discuss their involvement with NAMI and to invite the community to support mental health for all through NAMIWalks.
DIALOGUE: NAMI Albany invites community to support mental health at NAMIWalks
One in five Americans live with a mental illness. The Albany chapter of the National Alliance on Mental Illness wants to remind the community that no one has to face it alone. Ngina Mandouma and Kelly Wesselman joined Sunday’s Dialogue to discuss their involvement with NAMI and to invite the community to support mental health for all through NAMIWalks.
DIALOGUE: NAMI Albany invites community to support mental health at NAMIWalks
One in five Americans live with a mental illness. The Albany chapter of the National Alliance on Mental Illness wants to remind the community that no one has to face it alone. Ngina Mandouma and Kelly Wesselman joined Sunday’s Dialogue to discuss their involvement with NAMI and to invite the community to support mental health for all through NAMIWalks.
Legendary Phoenix Suns Coach Names Shawn Marion for Major Honor
Mike D’Antoni insists the "seven seconds or less" era's success demands Shawn Marion’s Hall of Fame induction, cementing the versatile forward's legacy as a defensive powerhouse.
Red card dished out in choppy Madrid derby 📸
The action inside the Metropolitano has been the focus on Sunday as Atlético de Madrid hosts Real Madrid. After a choppy first half, a red card led to the first goal. Deadlocked by the break thanks t...
Celtic 'passive' & 'in trouble'
Celtic sustained a third defeat in a row after Rangers left Glasgow's east end with a 1-0 win in Sunday's Scottish Premiership match. For Martin O'Neill's side, it followed last Sunday's 3-0 League Cup loss away to Rangers and a midweek Europa League defeat at home to Ferencvaros. Former Celtic captain Scott Brown was on punditry duty for BBC Scotland and shared his thoughts on the game.
How Philadelphia can attack Tennessee’s biggest defensive weakness
Philadelphia can use motion, play-action and its receiving depth to challenge Tennessee’s rebuilt secondary Sunday
Fiorentina frustrate Napoli with Serie A draw, Como upset
Fiorentina maintained their unbeaten run under coach Paolo Vanoli with a 1-1 draw against Napoli on Sunday, before Frosinone pulled off one of the shocks of the Serie A season by beating high-flying Como.La Viola showed improvement under Vanoli by beating Venezia in Serie A and Pisa in the Coppa Italia in his first two games, and the upturn in form continued as they fought back to claim a draw that moved them onto four points, with Napoli on seven -– six from the summit.
Live updates: Manchester United vs Fulham at Craven Cottage
Manchester United need to return to winning ways when they take on Fulham at Craven Cottage on Sunday.Michael Carrick is under pressure and only a win will do before heading into the international bre...
Rain in the forecast for Packers-Jets in Week 2
The Packers and Jets will need to navigate wet and rainy conditions at MetLife Stadium on Sunday.
Man City outlast Sunderland in eight-goal thriller, Liverpool win
Brian Brobbey scored a hat-trick in a losing cause as Manchester City maintained their 100% Premier League start with a frantic 5-3 win over Sunderland on Sunday. In a game characterised by poor defending, City struggled to kill off the fired-up visitors at the Etihad Stadium, with Brobbey a constant thorn in their side.
Leeds United and Crystal Palace clash ends in stalemate
Leeds United stretched their unbeaten start to the Premier League season to five games with a 0-0 draw at home against Crystal Palace on Sunday.With the side unchanged from Monday’s commanding win o...
Fed's Kashkari says inflation is still too high across US economy, in Fox News interview
Minneapolis Federal Reserve President Neel Kashkari said on Sunday that inflation is too high across all sectors of the US economy, not just in rising oil prices.
Zara Larsson Hits Her Career Peak As Her Album Mounts A Comeback
Zara Larsson’s ‘Midnight Sun’ debuts in the Vinyl Albums top 10 as the project and its title track surge across multiple Billboard charts.
🚨 Manchester City wobble, Liverpool steady themselves!
Three goals conceded, but… the win is there! A strange afternoon for Manchester City at home, as they ran out 5-3 winners against a tough Sunderland side.Dutch international Brian Brobbey grabbed a ...
Letter to the Editor: Nasty politics have come to Flagstaff
Nasty politics come home to Flagstaff? An ugly mailer from our Chamber of Commerce features wild deceptions about council member Austin Aslan's record.
Haaland completes Premier League set by scoring against Sunderland
Erling Haaland’s goal against Sunderland today means he has now scored against all 25 sides he has faced in the Premier League. Men's Team Haaland becomes top scorer in Manchester derbies in Premier...
STRING’S SUNDAY MORNING THOUGHTS
Tbh before this season started I thought this was the year I made a clean break from writing for GBH. It’s been a good 15 year run and it’s time to just be done. And then yesterday happens…and here I am again on a Sunday morning needing to process my thoughts. I hate it but […]
Sunday Patriots Notes: Defense keeps searching for takeaways
Notes and thoughts on the Patriots defense, the home opener blues, Mike Smith’s connection with Aaron Rodgers, and more.
Guardians News: One More Game Against the Athletics
News and Notes for Sunday, September 20th, 2026
Optimism and tight polls: Can Florida Democrats flip Sunshine State blue in 2026?
Florida Democrats gathered in Miami with renewed hope as tight polls signal potential turnarounds in key 2026 midterm races.
Mapping tsunamis, building trust
While taking a quick shower before her son’s fourth birthday party on Dec. 26, 2004, tsunami scientist Elena Troshina heard the phone ring. Deciding it was worth jumping out, she
Celtic suffer derby defeat at home
Scottish PremiershipSunday, September 20, 2026Celtic Park, GlasgowCELTIC…ORANGERS…1(Naderi 33)Celtic suffered a 1-0 defeat at home to Rangers for their first Premiership loss of the season and bri...
Lopez strike seals Wolves win in Black Country Derby
Wolves claimed local bragging rights on Sunday as Fer Lopez’s second-half goal secured a 1-0 victory over West Bromwich in the Black Country derby.Wolves dominated the opening stages and could easil...
Aidan O’Connell ruled out for personal reasons
The Las Vegas Raiders will be without Aidan O’Connell because of personal reasons on Sunday
Hundreds line up for free caffeinated drinks at 7 Brew stand in South Charleston
A crew of about 30 gave away free sweet, colorful caffeinated iced drinks on Sunday, Sept. 20, 2026, at the not-yet-opened 7 Brew location in the Park Place retail center in South Charleston, West Virginia. The Arkansas-based chain expects to open at 5:30 a.m. on Oct. 5, 2026.
How Toronto Blue Jays' Playoff Chances Stack Up Entering Sunday
After consecutive losses against the Texas Rangers, the Blue Jays have their backs against the wall.
3 bold predictions for Broncos’ game vs. Jaguars
Here are our bold predictions for the Broncos' game against the Jaguars on Sunday.
This Week in Purple: Here for the fall
Colorado Rockies news and links for Sunday, September 20th, 2026
Entertainment Stars Jeon Won-ju, Go Ji-yong, Han So-hee Spark Controversies
Entertainment Stars Jeon Won-ju, Go Ji-yong, Han So-hee Spark Controversies Weekly roundup includes fee disputes, backlash, custody battle, and verbal misstep
Who's in, who's out for Bears-Vikings in Week 2?
The Chicago Bears and Minnesota Vikings square off on Sunday. We're keeping track of the latest injury updates and inactives.
Trump says proposed DC arch will double as military complex
President Donald Trump on Sunday provided a new reason behind his proposal to build a 250-foot triumphal arch directly across Arlington National Cemetery, saying the structure would double as a “top grade Military Complex.”
Serie A official line-ups: Frosinone vs. Como
Frosinone welcome Como to the Stadio Benito Stirpe on Sunday afternoon, as both teams look to extend their good start to the campaign.It kicks off at the Stadio Benito Stirpe at 14.00 UK time (15.00 C...
Arizona State athletics events, Sept. 20-26
The Arizona State football team is enjoying a week off but there will be plenty of other Sun Devil squads in action this week.
City make 10 changes for Sunderland clash
City have made 10 changes for our Premier League clash with Sunderland from the side that beat Norwich City in the Carabao Cup in midweek. Men's Team He’s a truly, truly special person – Donnarumm...
49ers Announce 2 Roster Moves Before Dolphins Game
The San Francisco 49ers made their roster moves official Saturday ahead of Sunday’s home opener against the Miami Dolphins at Levi’s Stadium. Rookie wide receiver De’Zhaun Stribling landed on injured reserve, while defensive lineman Ogbo Okoronkwo was promoted to fill the vacated roster spot.Stribling’s Injury and Recovery TimelineStribling underwent surgery Wednesday to repair a ruptured […] The post 49ers Announce 2 Roster Moves Before Dolphins Game appeared first on HEAVY.
NFL Sunday Night Football best bets Week 2
Sunday Night Football brings the Indianapolis Colts to Arrowhead to face the Kansas City Chiefs, and there are several player props worth targeting. Here are four bets for the Week 2 NFL matchup. MORE: Bold predictions for Week 2 of…
Myanmar Politics
Khin Yi, Lower House Parliament Speaker and newly elected chairman of the Union Solidarity and Development Party (USDP), speaks during the party's conference at Party Headquarters in Naypyitaw, Myanmar, Sunday, Sept. 20, 2026. (AP Photo/Aung Shine Oo)
New York Jets Flight Connections 09/19/26
Happy Sunday, Gang Green Nation! The Jets look to improve to an improbable 2-0 today if they can upset the Green Bay Packers in their home opener. A win wouldn’t just give the Jets a hot start. It would provide some breathing room with a difficult two game road trip coming up. The Jets could […]
Bengals vs. Texans news and pregame discussion
The Bengals have a huge AFC matchup on Sunday afternoon.
TV broadcast maps for Week 2 of 2026 NFL season
There's a full slate of NFL action Sunday on CBS and FOX. Here's a look at the Week 2 TV coverage maps.
Sunday Night Football: How to watch the Indianapolis Colts vs. Kansas City Chiefs game tonight
How to watch this week's Sunday Night Football clash between the Colts and the Chiefs.
Lee Health must resolve UnitedHealthcare dispute
Letters to the editor for Sunday, September 20, 2026
Byron Donalds takes his testimony to Boca Raton
'We invite everyone to come and be part of this special Sunday service.'
Sunday football open thread
It’s the last Premier League football for three weeks, as the new, ridiculous super-international break starts tomorrow. However, there’s plenty of woso to come, with Spurs Women playing FIVE MATCHES before the men play another game. That said, we might as well have an open thread for the remaining Premier League matches today in addition […]
Minnesota Vikings vs. Chicago Bears: How to watch the NFL Week 2 game, channel, streaming info and more
How to watch the Vikings play the Bears this Sunday.
Fiorentina vs Napoli
All eyes are on the Artemio Franchi in Sunday’s early Serie A kick-off, as Fiorentina vs Napoli contest what promises to be an important game for both teams.Neither have started the season in partic...
PSG XI vs Marseille – Predicted lineup and team news
PSG will be aiming to record a third consecutive victory in all competitions before the first international break of the season when they travel to face Marseille on Sunday.PSG head into Le Classique ...
Bundesliga Sunday on OneFootball, plus loads of Brasileirão: fixtures 📲
Today's Highlights 🔥Bundesliga (German Championship)10:30 – Bayer Leverkusen vs RB Leipzig – OneFootball PPV12:30 – Schalke 04 vs Elversberg – OneFootball PPV14:30 – Paderborn vs Hoffenhe...
German elections under way which could decide fate of Chancellor Merz
The chancellor is facing intense political pressure which will increase if his party struggles in Sunday's polls.
World Organization for Science Literacy launched in Beijing
The World Organization for Science Literacy was launched on Sunday at the opening ceremony of the 2026 World Conference on Science Literacy in Beijing.The organization is an international scientific and technological organization initiated with the support
🗞️ Front pages: King Raphinha reigns on derby Sunday
Sunday’s front pages are split between an immeasurable Brazilian and an elite derby.Raphinha scored a hat-trick in Seville, taking his tally to twelve goals in seven matchdays, and Barça head into ...
Three Titans players Philadelphia must locate before every snap
Jeffery Simmons, Calvin Ridley and Chimere Dike can alter Sunday’s matchup if Philadelphia can't account for their productivity
AC Milan vs Lecce – Predicted lineup and team news
AC Milan will aim to keep their perfect, unbeaten run alive in Serie A this campaign as they host Lecce at the San Siro on Sunday, in what is their last outing before the international break arrives.T...
Panthers Add 1st-Round Pick to Week 2 Roster
The Carolina Panthers head into Sunday of Week 2 looking for their first win of the season. They’ll take on their NFC South rival Atlanta Falcons, who are also 0-1. Something has to give. The Panthers were 59-37 losers to the Chicago Bears in a Week 1 game that had more points than any opener […] The post Panthers Add 1st-Round Pick to Week 2 Roster appeared first on HEAVY.
Hollywood thinks this is all a game
Video game adaptations are big business, and the entertainment and gaming industries are fully in co-op mode.
Bay Area sports calendar, Sept. 20-21
Fred Warner (54) and the 49ers will face the Dolphins at 1:25 p.m. Sunday. (KTVU 2, KTXL 40)
A Fiery Return To European Competition for The Lads
Amid fireworks, noise and sheer passion, Sunderland’s 2026/2027 European campaign got off to a perfect start.
Manchester City vs Sunderland – Match preview and team news
Manchester City will be looking to make it five wins out of five in the Premier League when they welcome Sunderland to the Etihad Stadium on Sunday afternoon. Enzo Maresca’s side eased to a 5-0 win ...
Manchester City vs Sunderland – Predicted lineup and team news
Manchester City host Sunderland at the Etihad Stadium on Sunday looking to make it five wins from five in the Premier League. Enzo Maresca’s side have won every game across all competitions since he...
Liverpool XI vs Bournemouth – Predicted lineup and team news
Liverpool travel to the Vitality Stadium on Sunday for Andoni Iraola’s return to former club Bournemouth, where he took charge of 127 matches and guided the Cherries to their highest-ever league fin...
Jaguars Must Commit to Running Game to Beat the Broncos
If Jacksonville wants to beat Denver on Sunday, it needs to commit to running the ball against Denver's top defense.
China keeps benchmark lending rates unchanged for 16th month in September
China kept its benchmark lending rates unchanged for the 16th straight month on Sunday, in line with market expectations.
Seattle Seahawks Lose Another Starter For Cardinals Game
The Seattle Seahawks announced Saturday that starting right guard Anthony Bradford is out for Sunday’s contest against the Arizona Cardinals; Mike MacDonald told reporters on Friday that Christian Haynes takes Bradford’s place in the starting lineup. In a corresponding move, the Seattle Seahawks promoted safety Rodney Thomas II, similar to the opening game against the […] The post Seattle Seahawks Lose Another Starter For Cardinals Game appeared first on HEAVY.
Carson Wentz Receives Harsh Ranking Among NFL Backup Quarterbacks
Despite a stellar three-touchdown debut, analysts remain skeptical of Minnesota's new signal-caller. Discover why critics view the former starter as a mediocre backup ahead of Sunday's showdown.
Dodgers on Deck: Sunday, September 20 vs. Giants
The Dodgers conclude their penultimate home series of the regular season, taking on the San Francisco Giants on Sunday afternoon at Dodger Stadium. After dropping four of their first five games to the Giants this season, the Dodgers have beaten their longtime rivals three games in a row through Friday night, all in Los Angeles. […]
He’s a truly, truly special person
City No.1 Gianluigi Donnarumma has lauded new boss Enzo Maresca as a brilliant coach and wonderful person. Men's Team Haaland the cover star for Sunderland matchday programme Donnarumma linked up with...
Sunflower Troupe seeks Four Corners playwrights for 2027 short-play festival
Selected works will be performed next summer
Two Key Steelers Declared Out for Sunday's Matchup vs. Patriots
Pittsburgh will head to Foxborough without a few important players.
Could Jaguars' TEs Make Big Impact Against Broncos?
The Jacksonville Jaguars are seeking another road victory in Denver this Sunday. Look out for the tight ends and running backs to make a big impact.
The Jets’ interception-less streak is incredible
One writer expects this streak to end on Sunday.
Galaxy S27 Pro and S27 Ultra reportedly getting major battery upgrade
Samsung’s Galaxy S27 Ultra and S27 Pro are expected to get major battery upgrades, with certification records pointing to typical capacities of about 5,700mAh and 5,200mAh, respectively. This would mark the most significant battery upgrade since the S20.
Peacocks vs Eagles: How to watch Leeds United this weekend!
Elland Road hosts another Premier League fixture on Sunday afternoon as Leeds United welcome Crystal Palace, with the Peacocks looking to maintain their place among the early pace-setters.Daniel Farke...
Steelers Make RB, CB Reinforcements Before Patriots Game
Ahead of Sunday’s road matchup with the New England Patriots, the Pittsburgh Steelers called up veteran running back Travis Homer […]
Farm Safety Week to Highlight Physical and Mental Health
If you think about farm safety, you may have images of tractors, grain bins, and other equipment in mind. But
Russian election observer loses consciousness during arrest by police, opposition party says
The three-day election, which began Friday and ends Sunday, features virtually no opposition and is all but certain to secure the Kremlin’s political dominance.
Analysis: O'Neil can be encouraged at team's display
Ipswich scored last-minute goals in their wins over Sunderland and Crystal Palace and their fans would have had hopes of more late drama when seven minutes were added on at Hill Dickinson Stadium. Town had sent on Zian Flemming, who scored their winner against Palace, but the 10 men could not score, with Flemming wasting a good chance in injury time when he fired over the top. Centre-half Issa Diop almost snatched a point right at the end, only for his effort to be charged down by a combination of Branthwaite and Garner.
Fulham vs Manchester United predictions: Premier League tips and odds
Both Fulham and Manchester United are already under pressure this season ahead of their meeting at Craven Cottage on Sunday (kick-off, 4.30pm), in the final Premier League fixture before the international break.
In January 2026, researchers completed a drilling project beneath 1,716 feet of ice in West Antarctica, recovering evidence of an ocean that once lay open to sunlight
The discovery rewrites Antarctica's climate history—and raises urgent questions about how quickly ice sheets can collapse.
Training: Final prep for Sunderland clash
Check out images from training on the eve of our Etihad encounter with Sunderland. Match Preview City v Sunderland: Kick-off time and TV information The Black Cats head to Manchester for a 14:00 (UK) ...
Official Galaxy Tab S12+ Keyboards Leak Online Ahead of Expected October Launch
Leaked renders from a retail listing reveal Samsung's official Book Cover Keyboard Slim and Pro Keyboard for the upcoming Galaxy Tab S12+.
How I underestimated how unpredictable mental health can be
The Lindsay Clancy trial is shocking, but the complexity of mental health and our inability to control everything should be humbling to us all.
Abracadabra, It’s Magic! Appearing at Lobero LIVE, Oct. 11
Lobero LIVE and Terry Hill present Milt Larsen’s It’s Magic! for two shows, 2 p.m. and 6:30 p.m. Sunday, Oct. 11 at the Lobero Theatre. It’s Magic! the
Key Injuries for Patriots, Steelers Could Determine Sunday’s Outcome
The New England Patriots and Pittsburgh Steelers are in jeopardy of missing key contributors that could affect the outcome of Sunday’s matchup.
Phoenix Suns Insider Provides More Insight on Duop Reath Signing
Discover how a clever contract technicality allowed Phoenix to secure the versatile big man with little risk, bolstering frontcourt depth while preserving crucial roster flexibility.
Haaland the cover star for Sunderland matchday programme
Erling Haaland is our cover star for the matchday programme for City’s game against Sunderland on Sunday. Interviews Maresca: Opening day win was important for current form The City striker is also ...
Steelers CB Joey Porter Jr. ruled out vs. Patriots
Per the Pittsburgh Steelers’ Friday injury report, cornerback Joey Porter Jr. (NIR/conditioning/back) is out for Sunday’s matchup with the New England Patriots.
Samsung Confirms Free Feature Upgrade For Millions Of Galaxy Phones
Samsung has officially confirmed One UI 9 is rolling out to Galaxy S26 phones today with 11 new features. Here's what's new and how to get the update.
The Big Holes in Wearable Heart Rate Variability And Readiness Scores
On September 9th, Apple announced it was revamping its Apple Watch Health Sensing System, rolling out a Readiness score (0 to 10), and increasing the frequency of heart rate variability (HRV) outputs 24-fold. This can be viewed as upping its competition with various other consumer wearable sensors. These “readiness scores” as a composite of multiple metrics, with heart rate variability (HRV) being front and center for most. The majority of Americans are now using wearable sensors, which equates to well over 100 million adults. HRV and Readiness scores are increasingly being marketed as a measurement of autonomic nervous system health, a digital marker for future disease, a clock for biological age, and a holistic metric to promote healthspan and even longevity. (Apple also introduced a new longevity tab and “Health Age”.) None of this has been proven. In this edition of Ground Truths I am going to review what we know about heart rate variability and readiness scores. Heart Rate Variability HRV is the variation in normal heart cycle timing. The variability of the heart rate, the barely perceptible millisecond changes in time between consecutive heart beats (see R-R intervals in the Figure below, left panel), is due to interplay between the sympathetic and parasympathetic (vagal nerve) inputs. Distinct from heart rate, individuals with the same heart rate can have very different HRVs. It is a rough reflection of the autonomic nervous system (ANS) activity, inadequate to say whether a person’s ANS function is abnormal. For more than three decades, heart rate variability (HRV) has been measured and several studies have found an association of low HRV and clinical outcomes, particularly a link with higher all-cause and cardiovascular mortality. There have also been less well established links of low HRV to risk of early cognitive impairment, dementia, mental illness, Type 2 diabetes and substance abuse. An important reminder is that HRV is a surrogate marker without any established cause-and-effect relationship. If you increase your HRV, that doesn’t mean it will improve health outcomes. In fact, there is no hard evidence for that. All that work linking to health outcomes was done with electrocardiogram (ECG) derived HRV. Now, in the era of consumer wearables, this is getting assessed differently, by optical pulse (yes, the lights you see) plethysmography (PPG) or what is called pulse rate variability (PRV). They are not the same, as shown below (right panel) and only concordant when the delay between the ECG and pulse is kept constant, which basically means at rest. I should mention there’s also what I will call MPV, a mattress mechanical movement sensor, a derived heart rate variability, that companies like Eight Sleep use, even further away from directly measuring HRV. HRV has not one uniform measurement but many different types of quantification, such as RMSSD, the magnitude of difference between successive R-R intervals of normal sinus beats (N-N) or SDNN, the standard deviation of NN intervals, both in milliseconds. SDNN is one of the so-called frequency domain HRVs (others are LF, HF, LF/HF). Different wearable sensors use different metics; Apple has relied on SDNN and nearly all of the others use RMSSD, which is generally considered the more accurate metric. There’s also the different length of time measured, such as for a matter of minutes, all day, or an overnight’s sleep. Short measurements are especially problematic since they don’t capture enough of respiratory modulation and other factors that influence HRV. Share Ground Truths How well does HRV correlate with PRV? There are very limited studies, especially independently done. One that is commonly cited was conducted by Air Force researchers in only 13 healthy adults assessing Oura ring 3 and 4, Whoop 4.0, and Garmin Fenix 6 and showed a correlation coefficient of 0.88 to 0.97 and a mean absolute percentage error from 6 to 10%. The correlation is not a perfect 1.0, but there’s at least a fairly high level of correlation. HRV is supposed to increase during the night due to takeover of the parasympathetic nervous system, and higher during deep sleep. A recent example of my 1 week, all day “HRV,” and one during sleep is shown below. As you can see, the N of 1 data are inconsistent for the same days from different sensors (Oura, AppleWatch, Fitbit Air, and Eight Sleep) by patterns, absolute numbers, and comparison with prior days and weeks. The largest study in over 8 million Fitbit users (the old version, not Google Fitbit Air, introduced in May 2026) gives you a sense of the effect of age, sex, and the 2 different main HRV (here PRV) metrics, with RMSSD on the left and SDRR (=SDNN) on the right below. That study, from data collected in 2018, is a major outlier, since all the more recent ones are tiny with respect to sample size. Many of the companies have not had independent evaluation of their HRV, such as Eight Sleep, but have published a low standard error on their website. There are some other published studies on the correlation between HRV and PRV, but they are all small and only in healthy adults. A scoping review emphasized the lack of study in underrepresented individuals, including the aged, people of color (which affects the PPG signal), and individuals who are underweight or obese. Add the typical adult age 60 plus with one or more chronic diseases. For example, one study in over 900 adults found poor correlation of HRV and PRV, non-uniformly underestimated across many chronic diseases (cardiovascular, endocrine, neurological, respiratory, and others), concluding PRV is “an invalid surrogate for HRV.” A recent systematic review of 43 studies comparing HRV and PRV found reasonable pooled absolute standardized error (HRV as gold standard) but only 10 of the studies provided quantitative synthesis in ideal conditions. Their main conclusion was similarly cautious: “PPG-derived HRV [PRV] should not be regarded as universally interchangeable with ECG-derived HRV across all devices, populations, and recording contexts.” Factors Affecting HRV and PRV That gets me to the long list of factors that affect HRV (and PRV) besides the device, the type of measurement (RMSSD, SDNN or others), the person’s signal, the sensor site, the duration of data capture, if weighting by sleep stage is used, how artifact is processed and corrected. And this list is not complete!: Oura puts out data from their community of users (who input data) on what affects their overnight HRV. The factors currently provided are: no alcohol (increase 8%), melatonin (increase 2%, float tank (increase 2%), wine (decrease 4%), and party (decrease 14%) in overnight HRV. Must be some big parties! Subscribe What is a PRV measurement good for? It has been falsely characterized as an index of “autonomic balance” and a specific indicator of stress. A 2018 review of the studies available for HRV and its relationship to stress, not using any of the current wearables, found that stress can lower HRV. But so can many other factors. The non-specificity of the signal, indexed to the table above, is striking. Evidence from a UK Biobank study of over 46,000 participants with actual HRV looked at genetically predicted HRV, a genetic risk score, that failed to show the expected HRV-mortality link, indicating that _HRV is likely not causa_l, but rather a reflection of person’s physiologic state. A review of consumer wearable HRV data from 5 longitudinal studies showed that nighttime PRV was not associated with perceived stress, and surprisingly higher HRV, in the largest cohort (N=717 participants), was correlated with higher stress. An Oura ring cohort of 525 first-year college students found a link between overnight PRV and perceived stress, but that was also seen with resting heart rate, sleep, and respiratory rate. Several very small studies have examined the relationship of HRV and athletic injuries or guiding training with mixed, and predominantly negative results. HRV biofeedback training with paced breathing had no significant effect on reducing stress or raising HRV, as demonstrated with sham controlled trials. When HRV for multiple days showed a decline in conjunction with body temperature, the Oura ring published data for prediction of Covid. The WHOOP company sponsored an observational study, published in 2026, of 30,000 users for 72 weeks, without a control group, that reported reduced alcohol intake (5.8 % points) by self-report. That doesn’t tell us much, and particularly about the merits of HRV for behavioral change. If you use the same device and conditions as longitudinal trends for multiple (at least 2-3) weeks that may be the one way to get something useful from the measurements. Data for overnight sleep with minimal motion and using RMSSD is the best proxy for real HRV. The reason to look at trends rather than any given night is that it more likely represents something, even though you won’t know with certainty what the “it” is. Keep in mind there are no data, no peer-reviewed evidence, to show that HRV fluctuation in-person has any correlation with health outcomes. Share Readiness Scores These are proprietary scores that integrate different metrics for each of the wearables: no algorithms have been disclosed. They are unvalidated against health outcomes. In a review of 14 composite health scores of readiness and recovery, HRV contributed 86% to the scores, followed by reading heart rate (79%), physical activity and sleep duration (both at 71%). That review noted the substantial variability in measurement protools and lack of standardization. Sleep staging is notoriously inconsistent and inaccurate by these sensors, which adds further to the HRV uncertainties for what the scores, which use sleep stage data, mean. Only resting heart rate has been shown consistently across devices to be extremely accurate. I’ve made a Table to summarize what we know about which metrics are included, the scores, any peer-reviewed studies that compared the readiness score with health outcomes, and the corresponding (if any, NA-not available) citation. You will note that some companies do not use the term “readiness," such as WHOOP for recovery, and Garmin, which has 2 different scores, one of which is Body Battery. Eight Sleep uses the term “Fitness Score.” They all include HRV; Apple includes a new metric they call “Recovery HRV” which among other components uses 7-days of sleep, but it is unclear what this means or how it is differentiated from other scores (there are clearly no data for outcomes). We have no knowledge of how the different components are weighted or whether any of these scores are better than resting heart rate, HRV alone, physical activity, or any other single metric. Since none of these are standardized, they are not interchangeable, so if you get a 90 for Oura that has no relationship to a 90 on a Google Fitbit Air. Notably, the company can update its algorithm for readiness score at any point without notification to device users. Without any useful evidence of actionability for these scores or established relationship with health outcomes, it is hard to make a case for their value. At the Apple recent announcement they showed their Readiness score (0-10) on the watch (Figure below) but there are no published data on this score, not even on their website. It’s available only on their new Watch Series 12 or Ultra 4 [of course, ;-)]. That exemplifies the problems with these scores, lack of data and evidence for being meaningful to promote health. Perhaps the best study (which isn’t saying much) is the WHOOP Recovery for golfer performance, because it did correlate with an objective outcome, even though there was no control group and the authors were all from the company. Among the 389 pro golfers, an absolute 10-per cent point increase in Recovery score was associated with about 0.5 fewer strokes per round. But that’s hardly a health outcome! WHOOP is also conducting a study in over 2,700 runners to see if their recovery score will be linked to less injuries and improved performance, but that is not yet published and has no control group or randomization. Putting This in Context For two decades I’ve been enthusiastic about the potential for digital health and particularly wearable biosensors. Over the years, we’ve seen some great progress for their ability to promote physical activity and accurately detect atrial fibrillation (the first FDA cleared deep learning AI for consumers). That work was the subject of rigorous research. But there are holes in the data and evidence for other metrics. One notable one is the “VO2 max” story that I wrote about earlier this year. At that time many subscribers asked me to cover heart rate variability, which I finally got to here. When I dived into the research and publication for HRV and readiness scores, I expected to find at least some that were of high quality and demonstrated their utility by linkage to health outcomes. To my surprise, I found none. The wearable sensor measurements for HRV (PRV) are, for the most part, accurate, but that validation work has only been done in small studies of healthy adults and does not take into account the long list of factors, from the device, software side, and the user side, that affect HRV measurements. Moreover, this metric chiefly relies on optical sensing and, as we have learned for heart rate PPG sensing, may be less accurate in people of color. Keep in mind that all of the health outcome association evidence comes from ECG-derived HRV; none are from wearable sensor data. I will repeat the key point: there's no peer-reviewed evidence to show that in-person HRV fluctuation—or efforts to raise your HRV— has any correlation with health outcomes. For those of you who look at your HRV on awakening, or even 2+ week trends of it being low, I hope this context helps to relieve any anxiety. Yes, low HRV (not PRV) has been shown to increase risk of some diseases as summarized above. But efforts to raise your HRV—a surrogate metric— has not been established for improving any health outcomes. HRV does not have any evidence of causality (the genetic evidence actually goes against this possibility). In this summary, I have not included data for other wearable sensors such as Polar, Samsung, Withings, Suunto, Amazfit, Coros, Ultrahuman, or additional mattress sensors. These are beyond my first-hand experience, and as far as I know from my in-depth review none have any peer-reviewed published data that differ from the 6 sensors I’ve reviewed here. From the points I’ve gone over above, we’re not ready for readiness scores. Besides being proprietary, they are predominantly based on metrics that have their own issues. It’s compounding the problem, like building a house without a solid foundation that has never undergone a rigorous inspection, and then selling it. Like I mentioned for PRV, you can look at trends over weeks rather than any single day, to get a handle, but even that may not be helpful. There’s simply no evidence that these scores meaningfully relate to health outcomes. I’d emphasize they might, but that requires doing prospective or randomized studies to prove it. None exist. There’s great promise for HRV/PRV utility_. For example**,**_ Prof Maiken Nedergaard, who discovered the brain glymphatics that are essential in eliminating metabolic waste products from the brain during sleep, has posited that HRV could be a non-invasive marker for neuromodulator oscillations, brain-body regulatory circuits, and brain clearance. That would be extremely useful, but like everything else on HRV and readiness scores it requires solid research and validation. The lay media isn’t helping much to get the story straight. Earlier this year The Economist published a piece entitled “The most useful indicator of your overall health” which ordained HRV as an “accumulated stress score.” That’s akin to the false assertion about VO2max: “V02 max is the singular most powerful marker for longevity.” As I’ve summarized here, that is not established. The fact is that so many things can lower HRV, including physical exercise (especially an intense workout), reduced sleep quality, stress, the list above, no less the device, signal, and software. Whatever fluctuations observed have not been correlated with any health outcome. Sadly, “datamaxxers” are widely using HRV and readiness scores that have never been validated to mean anything. We already know that for some people using the sensors for sleep metrics, it can induce “orthosomnia,” an obsession to get high sleep quality, with associated high levels of anxiety. In an experiment done by a company to promote sleep quality for its employees, “For those employees who did use the trackers, many reported feeling perfectly rested until their tracker told them they had had a terrible night. Others were told that they had slept like a baby when they had actually been lying awake worrying about the quality of their sleep. “ The same problem can result from preoccupation with HRV or readiness scores, with anxiety that would lead to further reduction in both. It you are using a wearable like >100 million American adults, it’s OK to look at these data, but contextualized with the major caveats reviewed here. If you are one to require evidence that HRV or readiness scores are linked to health outcomes, you may not even want to look. The companies make it hard to turn them off! Let me end with the companies that make and sell wearables. Apple’s doubling down on HRV (24-fold more reporting and heart rate very 5 seconds) and introduction of a Readiness score tells us that consumers have bought into these metrics and they are joining the club. However, all of this is occurring with a backdrop of tens millions of users, claims about the data that are not backed up by adequate evidence, marketing way out in front of whatever limited data exists, and not being transparent about their readiness score algorithms. The companies can well afford to do the research that is needed to connect these metrics with health outcomes show, once and for all, that increasing HRV or using readiness scores promotes our health. If they believed and invested in the products they are selling, we’d not be in this position of not knowing. That’s essentially where we are with HRV and readiness scores. Perhaps someday this will change and we’ll have good reason to embrace them. NB: I wrote this post. No AI. I have no conflicts of interest with any of its content. Loading... Ground Truths has 215,000 subscribers from every US state and 214 countries. There are over 300,000 followers of Ground Truths so more than 90,000 folks who can easily convert to be free subscribers. Your subscription to these free essays and podcasts makes my work in putting them together worthwhile. If you’re not a subscriber, please join! If you found this interesting PLEASE share it! Share Ground Truths The proceeds from all voluntary paid subscriptions go to support our summer internship program. It enabled us to accept and support a record number of 62 summer interns that joined us in 2026! These are high school, college and medical students selected from thousands of applicants. We couldn’t do this expanded program without the funds coming in through Ground Truths. Thank you!
Too Much or Too Little Sun Exposure Can Impact Your Health — Here's How to Strike a Balance
Learn more about the impacts that too much or too little sun exposure can have on your skin health and vitamin D levels, and how much sun protection you may really need.