My natural sleep cycle doesn't seem to conveniently fit into a 24-hour day. If I go to bed when I'm tired and wake up naturally, I find that each day I'm waking up about an hour later. I have experienced this twice in my life, so far. Once, after selling a business and taking some time off, I quit drinking coffee and after the effects wore off, that was my pattern. The second time was more recent. It isn't a problem, but it is interesting.
Anyone else experience anything like this?
As John Tyrrell has said, it is your Circadian rhythm which runs around about a 25 hour cycle. The variability of the cycle is partially based on light levels but also on an inbuilt body clock. Look up Michael Siffre who produced a number of studies on the matter.
If you are having trouble keeping a good sleep pattern, then you will need to cleanse your sleep habits. Failing that, see a Doctor and get some Melatonin prescribed.
@David_Cooper Daylight changes as the year progresses so our circadian timer has evolved to deal with it.