I didn’t used to have a harmonious relationship with sleep. In fact, sleep used to be a source of anxiety for me. I have parasomnia, an amalgam of disorders that, occasionally, give me hypnopompic hallucinations, night terrors, and, most dangerously, somnambulism, which has led me to drive while sleeping and scare the living piss out of my poor husband after we watched Paranormal Activity together (it didn’t help that I was mutely standing over him at 4:15 AM with my eyes wide open).
So it should come as no surprise that I’ve built quite the relationship with my own sleep metrics and have more than a layman’s knowledge of sleep science. Which brings me to this article.
For a long time, I was highly skeptical of so-called “top sleep trackers and apps.” I knew just how intensive clinical sleep studies are.
When you go in for a study, you’re monitored by a team of polysomnographers overnight. They connect lots of wires to your head and your chest and clip a heart monitor to your finger. Your room is perfectly controlled—from room temperature to light allowance. You’re so wired up that if you decide to get up to go to the bathroom, you need a clinician’s assistance to get there.
So how could some single thing that just sits on your wrist, finger, or bed possibly compete?
For answers, I turned to some of the experts for commentary. What I found surprised me.
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What does sleep have to do with longevity?
Let’s say you eat well, you exercise regularly, and you get adequate sleep. I’m going to take one of these strengths of yours away. Either your diet, your exercise regimen, or your sleep is going down the toilet. There’s a catch: I’m allowing you to designate one of the three as untouchable. Which one do you guard?
If I had to choose one to save, it would be sleep. Not even close.
I have to agree.
I mean, if you don’t sleep, you die.
Okay, that might be a little hyperbolic. There hasn’t been a human clinical trial of how long humans can go without sleep because that would be super unethical. But there have been other clinical trials with mammals, and it appears that, at least in rats, most can’t live a full month without a bit of shut eye. I do not volunteer to see that kind of person I’d become after a full month without sleep.
While we still don’t entirely know why sleep is important or how it works, we do know that quality sleep—and for not too long and not too short—is one of the foundations of being healthy. In fact, a 2017 article found that sleeping outside of six to eight hours a night leads to “an increased risk of all-cause mortality and cardiovascular events,” regardless of the subject’s gender.
Research published in the European Journal of Epidemiology also finds that “The effect of short and long sleep duration on mortality was highest among young individuals and decreased with increasing age.” According to the same study, both too much and too little sleep and all-cause mortality stop correlating after the age of 65. There are three theories as to why this may be:
- Chances of dying increase with age, which may dilute the effect sleep has on mortality.
- Older people may represent a “survivor” population that is particularly resilient against the negative effects of poor sleep duration.
- Older adults are less accurate when reporting their sleep to the researchers because they’re more likely to be retired, and therefore do not have to regularly wake and go to sleep at an established time.
That all said, the younger you are, the more sleep matters to your overall health.
Sleep-deprived humans also tend to do things that are more likely to get themselves—and others—killed. The Cleveland Clinic lists the following repercussions for sleep deprivation:
- Daytime sleepiness (admittedly, this one is obvious)
- Impaired memory
- Moodiness and relationship strain
- Disinterest in exercise and other normal everyday activities
Additionally, a study published in BMC medicine found that “9% of all motor vehicle accidents could be attributed to people sleeping less than seven hours a night.” Fatigue also contributed to the BP Refinery Explosion (PDF), the Chernobyl Explosion, and the Space Shuttle Challenger Explosion (PDF). The American Psychological Association finds that “Accident and injury rates are 18% greater during evening shifts and 30% greater during night shifts when compared to day shifts.” A 2007 study found that there is an estimated $136.4 billion dollar cost to the economy each year due to “fatigue-related, health-related lost productive work time to employers.”
In other words, sleeplessness is dangerous and costly, and not just to the individual.
And sleep quality matters too.
For example, obstructive sleep apnea is widely “underrecognized and underdiagnosed.” But individuals with moderate to severe sleep apnea have a notable elevated risk of mortality from cancer and stroke compared to individuals without. People with obstructive sleep apnea and parasomnia have higher risks of breast cancer. The same study finds that parasomnia also increases the risk of oral cancer.
When looking at sleep stages, Harvard’s Health Blog recently wrote a great roundup of the research correlating less REM sleep with increased mortality. Drs. Epstein and Cai write, “Short REM may also be a marker of a sick or aging brain; less REM sleep has already been tied to a greater risk of dementia. Overall, ensuring adequate REM sleep is important to protecting your long-term health.” Tracking your sleep stages could help uncover neurological problems far before you would notice them without equipment.
In other words, taking stock of your sleep duration, your sleep quality, and your sleep stages could help you live longer. The question then becomes: what’s the best way of going about doing it?
The top sleep trackers and apps in 2021
The founder of SleepStandards.com, Chris Norris, points out that one of the benefits of sleep trackers and apps is that they “are available without prescriptions,” which makes accessing one’s own health data way more affordable than getting information through polysomnography (PSG). Alex Savy, founder of SleepingOcean.com, adds that sleep monitoring “can aid clinical diagnostics as well by providing long-term reports of patients’ physical activity.” He, along with several other physicians that I talked to, suggested that the best sleep apps and trackers provide information about the following:
- Resting heart rate
- Sleep cycles
- Bedtime and wake time
- Sleep quality
In addition to those biomarkers, the very best sleep trackers and apps also provide feedback on sleep apnea (in the form of tracking snoring or blood oxygen levels), have proven their data accuracy in a clinical setting, and syncs with other health apps.
I decided to order these trackers and apps by ease of use, from most set-and-forget to use to least. That means I prioritized battery life for trackers, which are all easier to use than apps for their automated tracking, and depth of information for sleep apps.
The top sleep trackers for 2021
The vívosmart® 4 features Garmin’s “Advanced Sleep Monitoring” service, which tracks the wearer’s blood oxygen saturation, sleep stages, heart rate and heart rate variability, and how many breaths are taken per minute. Its battery life lasts an entire week, which means you can forget about it on your wrist most of the time. Garmin’s sleep tracking isn’t groundbreaking, but it is accurate and it’ll get the job done for anyone interested in quantified self and sleep trackers for longevity.
While Garmin does provide several trackers with “Advanced Sleep Monitoring,” I settle on this one because of the long battery life, minimalist presentation, and low cost for the purpose of this roundup.
Clinical trial: A study published in Neurology found that Garmin’s trackers were able to track sleep stages moderately accurately. Garmin sponsored the study.
Battery life: 7 days
2. Oura Ring
Several experts I spoke with enthusiastically endorsed the Oura Ring. Christopher Babayode, a jetlag consultant, tells me that he encourages his clients to use it. Babayode likes it for its comfort, accuracy, and modes of data collection. And for $299, it better report on a whole lot!
The Oura Ring delivers. It shares basic metrics, like heart rate, sleep stages, and heart rate variability, and also throws in some other important metrics like sleep efficiency, sleep latency, and time in bed (versus time asleep). They also have a collection of “readiness” scores, informing the user of how well rested they are for the upcoming day. Premenopausal females can also take advantage of the Oura Ring’s nighttime temperature readings to predict their periods, which may be particularly helpful if your sleep is sensitive to hormonal changes.
Clinical trials: The latest trial on Oura ring accuracy was conducted by a third party—the study was published in 2019 in Behavioral Sleep Medicine. Researchers found that when compared to PSG, the Oura Ring had a 96% sensitivity to detect sleep, but was a little shaky when differentiating sleep stages.
Battery life: Up to 7 days
Cost: Starts at $299
The WHOOP Strap 3.0 emphasizes actionable sleep data. Yes, it offers insights into sleep stages, respiratory rate, and sleep efficiency like the other trackers, but it’s an athlete-focused product. Just how much sleep do you need to recover from a huge workout? Or to catch up on your sleep debt? As a top sleep tracker, the WHOOP Strap 3.0 goes beyond traditional sleep tracking and focuses on all aspects of recovery, making it an excellent choice for any athlete. I unfortunately have to add that the WHOOP Strap 3.0 doesn’t have a display—the user will have to check in on their sleep through an attached app.
Clinical trial: A 2020 study published in the Journal of Clinical Sleep Medicine found that Whoop was highly accurate in monitoring sleep, sleep stages, heart rate, and respiratory rate. No affiliation with WHOOP was declared in the study.
Battery life: 5 days
Cost: Starts at $30/month for the app subscription; the band itself is free.
A list that champions sleep wearables wouldn’t be complete without a Fitbit. Fitbit, like Garmin, offers a number of sleep trackers with the same sensors and insights, so which Fitbit came down to a point of preference for this list—I chose the Versa 3 because while the Sense could be outfitted to be a better sleep tracker for women because of its skin temperature detection functionality like the Oura Ring, it’s not set up that way. Therefore there’s no reason to pay an extra $100 for the feature. Fitbit’s Versa 3 tracks sleep stages, assigns a sleep score (“based on your heart rate, the time you spend awake or restless, and your sleep stages”), and estimates oxygen variations.
I do have to slap Fitbit a bit on the wrist (or my wrist, in this case)—some of the more interesting data you can get (your sleeping heart rate and restlessness) is behind an additional $9.99 a month or $79.99 a year paywall.
Clinical trial: A 2019 study published in the Journal of Medical Internet Research provided a meta-analysis of published, peer-reviewed journal articles covering Fitbit devices and sleep tracking. They found that “newer” trackers, especially models that offer sleep-stage analysis, were moderately accurate in providing sleep stage feedback.
Battery life: Up to 3 days
5. Sleep Watch with Apple Watch Series 6
By itself, the Apple Watch Series 6’s sleep app doesn’t compete well with the data provided by the other best sleep wearables for 2021 mentioned on this list. However, if the user downloads Sleep Watch, a compatible sleep app that syncs with the Apple Watch, users get access to critical information about their average sleeping heart rate, sleeping heart rate variability, and sleep debt along with other sleep metrics. Sleep Watch also offers a premium subscription that offers smart bedtime recommendations, day-to-day sleep comparisons, and personalized sleep improvement goals powered by machine learning.
Because of the affiliated cost, I would only recommend Sleep Watch to those who already own an Apple Watch.
Clinical trial: A study published in the December 2019 issue of Sleep found that third parties could use Apple Watch data to calculate sleep stages with modest accuracy. The study does not specify which Apple Watch was used by participants. The study was not associated with Apple or Sleep Watch.
Battery life: Less than 18 hours when using Sleep Watch
Cost: $3.99/month; the Apple Watch Series 6 starts at $399
The best sleep apps for 2021
Before diving into outstanding sleep apps, it’s worth noting that, when compared to wearable sleep trackers, sleep apps are especially poor for recording relevant personal sleep data. For example, one study in the Journal of Clinical Sleep Medicine found that one particularly popular app was fairly good at detecting whether the user was awake or not, but otherwise couldn’t detect much other accurate sleeping information. Another 2016 study found that of 51 popular sleep apps featured in the Play and iOS stores, none were clinically verified.
With that said, a 2017 study published in Preventive Medicine Reports found that sleep apps could help with forming and sustaining best practices for sleep hygiene. While I’m dubious of some of the data that’s presented by any sleep app, I do think that the following options offer better insights than others.
SleepScore makes use of your smartphone’s detectors to get about as accurate as you can with no-touch sensors—and they’ve proven it. For example, SleepScore relies on ResMed’s algorithm for bedside monitoring. ResMed’s devices were used in a clinical trial that was published in Sleep. Researchers found that their devices—presumably similar to what SleepScore offers, were able to detect sleep about 95% of the time, but sleep stage recording was questionable. While ResMed didn’t directly sponsor the study, they did supply “equipment, supplies, participant compensation, and student stipends.”
Even so, SleepScore enables their users to estimate how long they spend in each sleep stage and their breathing rate overnight. The app takes this data and provides personalized insights based on that data—like when you should try to go to bed and when to quit caffeine for the day.
Cost: Free to $7.99/mo
Like Sleep Watch, Pillow is at its best when paired with an Apple Watch, but even without one, it’s still a useful app for iPhone owners. Pillow turns on your phone’s mic while you sleep, recording any sleep talking, snoring, and/or evidence of sleep apnea over the course of the night.
Pillow claims that it can sense the user’s movement and select the best time to naturally start an alarm. While Pillow does not have any clinical trials to prove this claim, thousands of user reviews swear by this feature.
Cost: Free to $4.49/mo
8. Sleep Cycle
Sleep Cycle uses your iPad or phone’s accelerometer and microphone to track your sleep. Simply place your device next to you—either on your mattress or your nightstand depending on your sleep setup—tell the app that you’re falling asleep, and then do so.
Sleep Cycle also offers plenty of self-reporting metrics to help correlate what activities help contribute to a good night’s sleep, like how working out (yay!) and stress (not yay!) impact a user’s sleep over time. The app also records snoring to potentially pick up on warning signs of sleep apnea. Sleep Cycle doesn’t have a clinical trial to back up its accuracy claims, but it does have over 120,000 reviews on the Play store alone, with the bulk of them professing enthusiastic support.
Cost: Free to $7.99/mo
More top sleep trackers and apps for 2021?
I passed up on several trackers and apps—like Withings Sleep and Beddit—while writing this review, mostly for lack of clinical trials or disheartening findings therein. With that said, I am curious about which apps and trackers you use—and which ones you think deserve a second look.
If you’re a spanner, how do you quantify your sleep? Do you find that the information is helpful? What did I miss while reviewing all the top sleep trackers and apps for 2021? Let me know in the comments for future article updates!