What Do Sleep Trackers Monitor?

A wide variety of sleep trackers have hit the market, with more being released all the time. Many are wearable trackers that you can strap to your wrist. Others clip on your pillow or sit on your bedside table.

Features of these devices vary, but some common capabilities include:

• Sleep duration: By tracking the time you’re inactive, the devices can record when you fall asleep at night and when you stir in the morning.
• Sleep quality: Trackers can detect interrupted sleep, letting you know when you’re tossing and turning or waking during the night.
• Sleep phases: Some tracking systems track the phases of your sleep and time your alarm to go off during a period when you’re sleeping less deeply. In theory, that makes it easier for you to rouse.
• Environmental factors: Some devices record environmental factors like the amount of light or temperature in your bedroom.
• Lifestyle factors: Some trackers prompt you to enter information about activities that can affect sleep, such as how much caffeine you’ve had, when you’ve eaten or whether your stress level is high.