In general, actigraphy is not powerful enough to distinguish You being awake in the bed and not moving – or you being out of bed for toilet from Your deep sleep phase. This means that it is not able to tell how long it takes you to fall asleep. It also gets confused when you go to toilet in the night. However, we have developed an experimental way of overcoming this deficit
a) Awake detection
You may turn the awake detection on in Settings > Sleep tracking > Awake detection.
The awake detection estimates the length of the awake phase in two ways:
- By comparing the length of the first light phase of your sleep with a standard, we can estimate how long it took you to fall asleep
- By considering unusual positions of your device, we can find time points in which You were awake and estimate from there. This works as an automatic pause.
b) Without using awake detection
Without using awake detection, we need a little help from you to correct Your sleep tracking data. Ideally You can use the sleep tracking pause feature whenever You are tracking but not sleeping.
Pause is available from the Sleep tracking screen using the Pause button. This will display the pausing dialog with the pause time left. Pausing is designed to finish without your further interaction. You may add +5 minutes anytime your feel your pausing requires more time.
Adding pause time may also be done without looking at the touch screen. This feature needs to be enabled in Settings > Sleep tracking > Volume and camera button effect. This allows to cap pausing at minimally 5 minutes every time your press the volume of camera buttons. If your device is tracking with screen on (see the next section for details), no other action is required. If your device tracks with screen off the sequence to cap pausing is to press the power button and than one of the volume buttons or camera button.
In case you already know your typical fall asleep sequence you can configure automatic pause time at sleep tracking start. This option is available in Settings > Sleep tracking > Delayed sleep tracking.
You can also edit your sleep graph ex-post in order to correct your wake up or before fall asleep periods. This can be done in the sleep graph detail screen. Graph detail screen is displayed, when you click on a graph on the screen that lists all your recordings. You can select the related portion of the sleep graph and choose MENU > Delete selected
Heart rates for awake detection
In contrast to manual techniques or estimates, using a heart rate sensor gives us an exact information about your awake times.
During sleep, your heart beats up to 10 BPM slower than when awake. Heart rate tracking together with actigraphy gives a solid overall picture about your sleep.
- actigraphy recognizes between light and deep sleep phases
- heart rates help to identify awake and asleep states
At the moment Sleep as Android supports most Bluetooth heart rate devices and in the current BETA version it supports some Android Wear devices equipped with an HR sensor. Please refer to Wearable for more details.