Of course, cramps at night can also come from over indulgence in alcohol. A friend of mine was advised by his doctor to cut down the alcohol as he was having frequent leg cramps (after frequent nights of drinking)... it solved his problem... but it is a little difficult for him attending Folk Clubs where real ale is consumed in copious amounts and sticking to mineral waters....   he still gets leg cramps but not so regularly... if you get my drift.