The non-prescription stuff that has helped me in the past with sleep is melatonin (I think it might not be legal in Europe but it's OTC in the US) and Dramamine. Yep, motion sickness medicine - the standard formula, not the non-drowsy stuff. It puts me right out unless I'm really really hypomanic.

Another approach that might help is progressive relaxation. I learned this technique in drama classes in high school and it would literally put the whole class to sleep! You can do a web search and find out the details. It sounds a little silly but it can work. You might be able to find an audio recording where someone with a very soothing voice guides you through it. Your mileage may vary, but maybe worth a try!