FAQ: Dreem Band's functioning

Written by Jonathan
Last update

Here are the answers to several questions about Dreem’s functioning.

How does the Dreem Band measure sleep onset duration?

Each morning, the Dreem app determines the time it took to fall asleep (Sleep Card "Falling asleep"). But how does the headband calculate this period?

1. Detection of the beginning of falling asleep (T0)

When you close your eyes for more than two minutes, the headband considers that this is the beginning of your falling asleep stage.

Please note :

  • If you open your eyes again for two minutes, the T0 does not start, you are still considered ‘awake’.
  • If, on the other hand, you open your eyes after two minutes, the headband will always consider that you are still falling asleep.

2. End of sleep detection (T1)

When you go into the light sleep stage (N2) or the deep sleep stage (N3) for more than two minutes, Dreem Band considers that this is the end of your falling asleep stage.

So, the duration of the falling asleep stage  is the difference between the beginning of falling asleep (T0) the end of the falling asleep (T1).

The falling asleep stage as well as all the data displayed on the application are based on good signal quality.

To make sure you have a good signal, visit our article ‘ How to: Improve the quality of your signal

How does the Band measure wakefulness?

Every 30 seconds, your headband calculates your sleep phase thanks to machine learning algorithms. Signs that allow the algorithm to determine that you are awake include:

  • Blinking
  • Your eyes are closed but your brain activity emits a frequency band (alpha) characteristic of wakefulness.
  • Your brain shows activity in the wakefulness frequencies (range, beta).
  • The accelerometer measures one or more significant movements.

Learn more about sleep stage detection.

Why are there occasional gaps in the hypnogram?

There are several reasons that your recordings may be incomplete:

  • Your headband moved during your sleep session and can’t pick up a good signal. For more information, visit our dedicated guide “How to: Put your Dreem Band on".
  • Your recording might have stopped because you didn't have enough battery.

Your band will automatically stop your record after one hour without any signal.

Why do the sleep stages appear wrong to me?

There are a few reasons why you may feel your sleep stages are wrong:

Poor signal quality. That may be caused by your headband not sitting correctly. Check out our guide ‘How to: Put your Dreem Band on’.

The hypnogram available in the ‘HOME’  section of the app has been streamlined for a better comprehension. This might lead to a few inconsistencies. For example, waking-ups displayed on the hypnogram might not be felt by users.

The subjective experience of well-being might differ from the calculation made by the band.