early/late activity and sleep
This is a typical CFS/ME question, and, after trying a variety of techniques, I end up in the same camp as many sleep experts.
The reason for this lag is tied to known regulation problems along the hypothalamus/pituitary/adrenal (HPA) axis, (for those who recognize CFS as a disease.) You can check part of this without elaborate laboratory tests. Just record how you feel at different times of the day, paying attention to some aspects mentioned here.
You start out at the low point in the cycle with cortisol levels that would make Addison's disease a possible diagnosis, if they persisted. (If you ignore warnings and push yourself long enough and hard enough, it is possible to end up with something very much like the real thing. Adrenal glands can burn out.) At this point in your cycle, you feel all those aches and pains. If you have an actual bruise or local inflammation, it will bother you most at this time. As you struggle out of bed, through breakfast, out of the house, etc. you will be calling on your adrenals to produce cortisol to get your body moving. They will be slow to respond.
Still, if you make it out of the house, though traffic, and into a doctor's office, (where you wait for half an hour,) you will look remarkably normal in a clinical setting. If your adrenals failed to respond, or you were not excited by the dangers of the road, you might reach your doctor in a state close to adrenal exhaustion -- assuming you were not involved in a traffic accident.
Every effort throughout the day makes similar demands for increased cortisol. At some point, usually late in the day, the rest of the HPA system begins to catch up. As your cortisol level rises, you become less conscious of those aches and pains, or exhaustion. By the time you reach normal bedtime, you may be ready to party, or as close to this as CFS/ME patients get.
In my opinion it is vital to begin applying the brakes hours before you plan to sleep. You've built up considerable momentum in your endocrine system (if experts will forgive me for such an analogy) and need to make an effort to slow down. You should start hours earlier by avoiding stimulants, except for a very limited amount needed to avoid disaster when you start your daily activity. (Automobile accidents have a decidedly negative effect on prognosis. Falls down stairs are no fun either. Even avoiding those, I've accumulated most of my bruises soon after starting daily activity.)
Even if you are getting adequate vitamin D from supplements, I recommend getting sunlight early in the morning to keep your diurnal cycle connected to the Sun. (This is also useful for jet lag.) When you need to shift your cycle, limit sleep during normal active hours to short naps. Do your best to get several hours of sleep at night. Sleep less than two hours will shortchange you on some aspects of rest. (In my case, less than four hours leaves me short of dreaming sleep.)
You can tell how you're doing with sleep by some indications which are also found in sleep clinics. If you are short of dreaming sleep, you start that phase of sleep more quickly to make up. (The technical term is 'reduced REM latency'.) If you are very short, you will be on the edge of hallucinating while awake. If a chance disturbance wakes you soon after you fall asleep, and you come out of a wild dream, this indicates your REM latency is low. This is a classic problem for CFS/ME sufferers.
I would be interested to hear from anyone who knows about diurnal variation in melatonin levels.