Sleep is really important for well-being and recovery. At medical technology conferences, sleep measurement and monitoring is very much where the buzz is.
Lots of fitness watches also provide sleep analysis but they require you to wear the watch. And if you are wearing the watch, you can’t charge the watch. The following companies are very much at the front of the race to catch the sleep market, and their devices are non-contact:
Apple’s Beddit: https://www.apple.com/uk/shop/beddit
There are many measures of sleep. In a sleep lab, there is a camera on the subject, EEG (brain waves), ECG (heart waveforms), Heart Rate, Eye Movement and Limb Movement are all recorded. Devices for measuring sleep at home measure a lot less. In a very interesting paper from 2017 Kaplan and colleagues (read an overview here) demonstrated that when you compare all the parameters that can be measured in sleep with how people feel they have slept, the most important factors are: total sleep time and sleep stage transitions. These can be measured with a fitness watch or with home use devices listed above.
For general information on sleep: https://www.sleephealth.org/sleep-health/
Apps: Autosleep for iphones has excellent reviews.
Note: there are serious factors which impact sleep which can only properly be assessed in a Sleep lab. If you are concerned that you are clinically affected by sleep issues – go to your doctor.