Best Sleep Tracking Apps of 2021

After finding a selection of the most popular sleep apps for mobile devices (with a few wearable options thrown in), we started testing. Using multiple phones and help from some Appsistants, we used each of the apps for several nights over a ten-day testing period. While this was not long enough to get all the benefits of tracking trends over time, it was enough to test the tracking functions, smart alarms, and relaxation content for falling asleep easily.

Since sleep is so individual and varies so much day-to-day, we didn't evaluate the apps on whether they improved sleep, but how easy they were to use, how extensive their relaxation content libraries were, how in-depth the data was and how clearly it was presented.

Many people download these apps looking for accurate data. However, no tracking app is as accurate as a medical sleep study. The apps don't measure sleep directly but look at behavioral proxies like breath, motion, or heart rate. Because of this, we didn't consider accuracy particularly, although we did note if we noticed an issue, like the app saying the person was asleep when they weren't.

Sleep apps can help improve sleep at three points: before sleep, during sleep, and waking up. They can offer sleep tips and audio content to help you wind down and fall asleep, track sleep cycles and record snoring/talking during the night, and supply a smart alarm to wake you up refreshed. Sleep Cycle shines in all three of these areas. Behind its simple, easy-to-use interface, Sleep Cycle is packed with features.

While Sleep Cycle's interface is highly usable, it's also pretty utilitarian... which is to say, not very pretty. It doesn't need to be, of course, but particularly for an app that users will interact with at the beginning and end of their day, a soothing and attractive design would be nice.

The sleep aid library is expansive but also difficult to access. You can't browse it outside of the app's tracking feature, meaning you have to start "sleeping" before selecting a track. While you can stop the tracking if you want to plan your bedtime in the middle of the afternoon, it would be nice if the sleep aids had their own tab that you could access separately.

But these are small quibbles about an app that is feature-rich and works very well.

In the drive toward the quantified self, we (or our apps) sometimes focus on collecting ever-more data without considering why we want it. Do we care about how many hours we spend in Phase 3 sleep? No. We care about sleeping well so that we can be healthy, happy, and productive. (Please note that if you are struggling with disordered sleep, these fine details may, in fact, be important. But that is something to investigate with a doctor, not an app.)

Sleepzy’s interface is simple and lets you jump right into sleep tracking. It opens on the Sleep screen, where you can set your smart alarm to ring within a half-hour period. The app uses your phone’s microphone to determine your sleep phase and wake you up when you’re least groggy. The app displays your sleep goal and duration at the top of the screen (set during onboarding), assuming you fall asleep when you begin tracking and wake up at your alarm. This provides a simple way to make sure that you’re setting yourself up for success.

AutoSleep’s interface is bright and friendly, an enticing app to return to each day. It uses the same circle icon that Apple Watch’s activity tracker does to motivate you to improve your sleep. Just as you close the circle in the activity tracker by getting enough steps, etc., you close the circle in AutoSleep by getting enough sleep.

This is an intuitive design, especially since Apple Watch users are already accustomed to it. However, some researchers have found that sleep trackers, in general, can increase anxiety around sleep, so if you find yourself worrying about having an open circle, remember that no app can perfectly measure sleep quality and that improving sleep is an ongoing process. 

Sleep as Android is a great and popular app for Android users. It’s well-designed, with trademark Android whimsy. Like most of these apps, it uses the microphone to measure sleep and provides graphs of different sleep phases through the night. One nice feature is that it has nap settings — good news for afternoon snoozers.

I tested most of the multi-platform devices on an iPhone, and some of them are known for offering a better experience on iOS, so some Android users might prefer this app to some that ranked higher on our list. 

There is considerable overlap in these apps' features, and I almost included Sleep Monitor as an Also Groovy pick. It has an appealing interface, lets you log things in your day that might impact sleep, and has an extensive library of pre-sleep relaxation content. This is a good one to try. 

Accuracy is both hard for apps to achieve and hard for users to measure, but Sleep Monitor did think I was sleeping when I was awake. Still, this is a solid and great-looking app.

One of the few apps that still uses an accelerometer (where you place your phone on your mattress). Since the two methods appear to be equally accurate, it seems like having your phone in bed with you is unnecessarily inconvenient. Other than that, the app works well and is easy to use. It has an Apple Watch integration, but we preferred Auto Sleep as a Watch app.

Sleep Booster’s greatest strength is its library of bedtime content. Like many of these apps, it has guided meditations, breathing exercises, soothing music, sounds, and sleep stories. But Sleep Booster lets you arrange these into a sequence to create a Sleep Ritual. 

Sleep Booster offers snore and voice tracking and a smart alarm. However, it doesn’t use breathing to detect sleep and sleep phase, so it is less useful as a tracker than other apps. If you want some help falling asleep, however, this is a good choice. 

SleepWatch is a sleep tracker for Apple Watch users. It tracks sleep rhythm, disruption, how long it takes to fall asleep, and how rested you feel in the morning. It measures heart rate, including how much your heart rate dips during sleep, which is known to be a health indicator. The app helps you improve your sleep and set sleep goals. Its features are similar to AutoSleep, but that app is a better value than Sleep Watch, which uses a subscription model.

While this article is not an exhaustive overview of wearables, this is the device that I use, so I thought I’d cover it. Garmin Connect tracks exercise (running, biking, workouts, etc.), steps, general energy level (a measure they call “body battery”), calories burned, food intake (if you pair with MyFitnessPal), and, of course, sleep.

The sleep tracker is passive, so you don’t have to tell it when you’re going to sleep. As far as I can tell, the sleep phase measurement is accurate — for instance, when I’ve woken up from a dream, the tracker has said I was in REM sleep. While passive tracking is a benefit because you don’t have to turn it on, I found the sleep ritual components of other apps on the list are really good for sleep hygiene. I also wish that the app integrated its features together. The body battery does this to an extent, but it would be helpful to have a pop-up that said something like, “you didn’t get much sleep last night. Take it easy on your workout today.”