Hazel, it may be partly boredom, but, based on my experience with my father, it is more likely that it is the natural progression of the illness. For many dementia sufferers their whole concept of time goes and everything seems to move earlier and earlier in the day. It is so difficult to reconcile this with a normal life. Dad started wanting to go to bed at 8.00 pm, then at 6.00, then at 4.00 in the afternoon. In the end I sometimes used to let dad have a nap late afternoon, then wake him up at 6.00 so that he would have his evening meal later, so stretching his 'proper' bedtime out to later. You just have to try all sort of 'tricks' to maintain the pattern of your own day and not worry too much about it when it goes awry!
Blue sea
Blue sea