Review of Sleep Cycle App: Tracking Movement to Time Awakenings

One of the most popular sleep-related apps (or applications) for iPhone, Sleep Cycle works by tracking your movements during the night in order to perfectly time your morning awakening. This app has some pros and cons.

How Sleep Cycle Works

Sleep Cycle relies on your smartphone's accelerometer to monitor movement. The idea is that you place your smartphone near you in bed and that it will register movements.

When you are in deeper sleep, especially REM sleep, it will document this stillness. When you are restless towards morning, drifting into lighter stages of sleep, it will seize on this wakefulness to alert you to get up for the day.

Pros

The interface of the app is slick. On the home page, there is an alarm clock where you can turn on the Smart Alarm. Then there are four tabs with other functions: Profile (for settings and personal info), Sleep (for sleep tracking and to set an alarm), Journal (where you can analyze your sleep quality), and Statistics (for deeper detail on your sleep data).

You can choose an alarm sound (including a favorite song) and set your snooze options. You select a 30-minute period that you wish to awaken during.

Then, each night after using it, it creates a summary on the Statistics page that includes a hypnogram (showing sleep stages) as well as your bedtime, wake time, and total and average sleep time.

The Journal tab will let you review your sleep quality for various periods (days, weeks, and months). It even offers a comparison to others in your country (as well as the countries with the lowest and highest sleep qualities). There are many graphs, tracking:

• Sleep quality
• Time you go to bed
• Time in bed
• Time you woke up
• Snoring
• Increased sleep quality
• Decreased sleep quality
• Sleep quality affected by air pressures
• Sleep quality affected by the moon
• Activity (steps)
• Sleep quality affected by activity (steps)
• Heart rate (bpm)
• Sleep quality per day of the week
• Time in bed per day of the week
• Overview (total nights, total time in bed, the average time in bed, shortest night, longest night, best night, and worst night)

Additional features are unlocked and available with the Premium version, including:

• Online backup
• Sleep aid (emits a soothing sound to help you fall asleep)
• Sleep notes (help you track how different activities, such as drinking coffee or working out, affect your sleep quality)
• Wake up mood (prompted upon awakening and saved)
• Weather (shows today's weather upon awakening)
• Heart rate (uses color changes in the tip of your finger to measure)
• Philips Hue (can use your linked lights to wake you)

Cons

The Sleep Cycle app does have some drawbacks.

Battery drain: In order to function, the program must run overnight and this will slowly drain your battery. Although it will no doubt vary with your battery's age, it drained mine by 20% over 8 hours.

The instructions recommend that you keep your phone plugged in, which could present a choking hazard should you become wrapped in the cord (though this risk is admittedly low).

Movements of others: The accelerometer will pick up any movements, including potentially those of bed partners or pets.

Sleep disruption: It brings your phone into the bedroom, and unless you put the phone in airplane mode, you may be bothered with calls, texts, and alerts throughout the night.

Inaccuracies: The sleep cycle hypnogram (for which the app is named) does not appear to be accurate. If you have a soft mattress pad or other bedding, the accuracy will suffer even more because movements will be missed.

Early waking: Setting a 30-minute window in which to have my alarm go off often left me getting less sleep than I desired. I would pick the later time to be the time when I absolutely had to wake up.

More often than not it would awaken me earlier, which left me with less sleep than I had desired. I never really felt that I awakened more refreshed because of the perfectly timed alarm clock.

Increased awareness: In general, having the phone in bed also made me more conscious of being awake or asleep, and this seemed to fragment my sleep.

A Word From Verywell

Therefore, though Sleep Cycle is an exciting development in inexpensive technology that may help us to monitor our sleep, it seems that it is really only accurate to track your bedtime and wake time.

It should not be used as an alternative to more sophisticated sleep studies. There are a lot of problems with its use, which give it a limited utility, and I would not recommend it for these reasons.