Frequent questions about Dreem functioning

Here are the answers to several questions you might ask regarding Dreem functioning. 

How the band measures sleep onset duration?

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

Detection of the beginning of falling asleep (T0)

When you close your eyes for more than two minutes, the band 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 falling asleep.

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, the band considers that this is the end of your falling asleep stage.

The duration of of falling asleep thus represents the difference between the end of the falling asleep (T1) and the beginning of the falling asleep (T0).

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 "Improve the quality of your signal".

How the band measures wake?

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

  • You blink;
  • Your eyes are closed but your brain activity emits a frequency band (alpha) characteristic of the alarm clock;
  • Your brain activity has a strong activity in the frequencies of awakening (range, beta);
  • The accelerometer measures one or more important movements.

Learn more about sleep stages detection.

How do you explain holes in the hypnogram?

Several reasons may explain that your recordings are incomplete:

  • Your band moved during your sleep session and doesn't receive a good signal. For more informations, go visit our dedicated article "Put your band on".
  • Your record might have stopped because you didn't have enough battery. Ensure that you have enough battery when you start a sleep session.

Please note that your band will automatically stop your record after one hour without any signal.

Why sleep stages might appear wrong to me?

Several reasons may explain that your sleep stages seem wrong to you:

  • Poor signal quality. That may be cause by a bad position of your band on head. For more informations, visit our dedicated article "put your band on head".
  • The hypnogram available on the "HOME" section of the Dreem app has been smoothed for a better comprehension. This might lead to a few inconsistencies. For example, awakenings displayed on the hypnogram might not be felted by the users.
  • The subjective level of well-being experienced might differ from the calculation made by the band.

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