Glasgow has a new groovy sleep centre, and some of their findings are interesting. So-called "sleep hygiene" - coffee, light in the room etc is a very minor matter. You have to have realy bad habits to make the difference. http://www.heraldscotland.com/news/health/winning-battle-against-insomnia-1.820586 Key point - "Sleep hygiene is a phrase which is commonly used with regards to the sleep environment but Prof Espie is not convinced of its relevance. âThere are a very small proportion of people who have got insomnia because of excessive coffee drinking or bedrooms which are too bright but very seldom are these the causal or the contributory factors to the insomnia. âWhen you compare sleep hygiene with CBT it doesnât work â it is no better than a placebo. The caveat to that is that if there are people whose sleep hygiene is very, very bad it would work for them.â " The real issues are different. [I've often wondered whether sleep disorders are one of those things which you would expect to find in any social group, not because they particularly benefit the individual, but because they benefit the group. Think of the advantages for a group of apes if one poor basta*d can't avoid stagging on every night, or who wakes up if a gnat farts].