Hi Katherine
You might have seen this recent article on the BBC website - interesting and timely!
http://www.bbc.co.uk/news/magazine-16964783I have often had spells of insomnia or maybe a different sleeping pattern. I think there are many reasons why it happens not least of which is a disturbed or less effective neuroendocrine system - perhaps something that many contributors to this site will have in common.
Best wishes
Tim