Have you tried taking anything for it? I've found that herbal stuff with valerian and hops in does the trick for me - the one I've been using for bad nights lately is the Sainsbury's own-brand one, which I think is called SleepEase.
Beware, though - if you take it and still don't sleep, you'll probably feel even groggier the next day, and some people report adverse reactions to valerian, such as nightmares.

Only two nights in a row? Lucky you. Some antihistamines (e.g. Piriton) are good for mkaing me drowsy.

Valerian makes me *incredibly* depressed. I find camomile tea is fine.