Random itching all over my body

Hi all I'm 22 and female, and for quite a long time I have been suffering from itching all over my body, mainly during the night. It will occur almost every single night and it is so irritating that I can never sleep! The only allergy I know of is of a certain body wash that I once used...but that was a few years ago and quickly stopped using it. I have had the itching for as many years as I can remember, but it has always been extremely rare and only seems to occur at night, just when I'm trying to sleep. (Typical.) However, last year when I moved house, I suffered from it slightly more often (roughly every few weeks?). And in March this year, my boyfriend and I moved into a flat together, and since then, I have had it very nearly every single night. I have tried sleeping tablets (just the over-the-counter type) but with no luck. Doesn't matter how tired I am. I have used the same body wash and shampoo for years and like i said, it used to pretty much never occur, so I ruled out allergies to that. The same applies to washing powder for my clothes etc, and my diet has always been the same. It only seems to occur at night, and it's mainly on my legs, but it does occur all over (from head to toe!). I haven't ever had any kind of rashes or visible problems. I sometimes apply moisturiser, which can help a little but not always. I try to avoid scratching at all costs! Erm what else...my boyfriend has never seemed to suffer from it (we share a bed). One thing I've heard that can cause itching is mould, and there is a little of it in my bedroom. However, when we moved in, we slept in a different room, and also, why would I have itched last year when I lived in a different house?? ARGH every night is almost guarunteed to result in no sleep at all...it's getting me down so much and I feel so exhausted. Funnily enough though....I usually find I can sleep during the daytime! I try to avoid it so I won't mess up my sleeping pattern, but it's the only time the itching isn't too bad.