Do Sleep Trackers Really Work?

Activity trackers are all the rage, and millions of wrists now sport
devices that monitor everything from your heart rate and oxygen consumption
to the number of steps you take each day.

Among their many functions, activity trackers can also shine a light on
your biggest source of inactivity: sleep.

But do they actually work? Read on to learn what sleep tracking devices can
tell you (and what they can’t.)

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.