The plan to turn off my drunken monkey brain at bedtime

"Sleep Hygiene" is excellent, and helps many people. (http://www.nhs.uk/Conditions/Insomnia/Pages/Treatment.aspx)

This is, put very simply, 'avoid stimulation, keep to a routine, fix the environment'.

Personally, if that's not working I had good experiences with Zopiclone. (Use it for 4 days to kick myself back into a routine. Don't use it for more that 14 days running or you get rebound insomnia).

Obviously, this isn't medical advice and I'm not a doctor and some serious conditions can affect sleep or wakefulness.