Although this is non-musical, it may be helpful information. I, recently, learned that using backlit devices, such as Kindle Paperwhites or iPad Minis, during the night, can suppress melatonin production & induce sleeplessness. The light fools one's body into thinking it's daytime, making it harder to fall back to sleep. This article
on how to sleep better, contains that & various other interesting information.

Wishing you restful nights,

bbc