Recently we have tested a smartphone armband for better sleep tracking. It brings the following advantages:
• improved accuracy of sleep tracking data and thus smarter and more pleasant wake up
• no worries of damaging your phone during sleep tracking
• immediate accessibility of sleep tracking options, alarm dismiss and other phone's functions, no need to search for your phone in the bed
• the same product may in addition be used for sports such as running or cycling
Another option to keep you phone in place during sleep tracking is Droidbed. It holds your phone while you are sleeping with Sleep as Android so that your phone is safe and still it receives all your body movement data.
Droidbed is a third party product which may be ordered at http://www.droidbed.com/.