Measurement Sleepphase

Source [1] is a app which measures the sleep cycle. This app can measure your sleep phase on two manners. The first one is with a microphone. Your smartphone determines on basis of the sound you produce during your sleep in which sleep phase you are. You’ve to place your phone like this:

The second manner is with an accelerator. Now, your smartphone determines on basis of your movements during the sleep in which sleep phase you are. You’ve to place your phone like this:

Calibration

Sometimes, you need to calibrate your smartphone one or two nights. This, because the microphone or accelerometer will be to sensitive. For example, you don’t only measure your movements or sounds, but also the vibrations and sound of a passing truck.

Sleeping with two persons

On their site, they claim that it also works when you’re sleeping together in one bed. This, because sound decays exponentially with distance. So the sound generated by your partner will have a much lower volume than sounds generated by you. The app communicates also over Wi-Fi with the device of your partner. This makes it possible to detect where in bed a sound originates from with an accuracy of 30 cm.

scientific background of measurements

The sleepphase could be determined on several ways. It is possible to measure your sleepphase with the aid of your heartbeat, respiration, movements and brainacitivity. Not all, but some of these are usefull for our technologie.

Brainactivity is naturally not possible to measure in our case. Also the heartbeat can't be measured on a distance yet. But the sleepphase can be determined with the aid of the movements and respiration. The muscle activity has a releation with the sleepphase.

As you can see in the figure above, the muscle activity decreases when you get into a deeper sleep. And the muscle activity is very high during the REM-sleep. The muscle activity is shown with electro-oculogram (EOG) and electromyogram (EMG). EOG measures the activity of muscular and autonomic functions, while EMG the movement of neck muscles measures.

A typical consequense of the higher muscle activity during the REM-sleep is a penile erection. Like you can see in the picture above, during every REM-sleep period are many penile erections measured. So if you wake up with an erection, you were probably in a REM-sleep.

The sleepphase can also be determined with the aid of respiration. As shown in the figure above, there is a strong relation between the breaths per minute and the sleepphase.

Sources (three App’s)

[1] Sleep Cycle(App), How does it works, http://www.sleepcycle.com/howitworks.html

[2] Pillow2.0 (App), https://neybox.com/pillow/

[3] [7] Azumio, Sleep Time (app), http://support.azumio.com/customer/en/portal/topics/667008-sleep-time/articles