Stan, I don't think it matters so long as you are consistent. Check out the book by Colin Espie, Chapter Five (or Section Five, I believe) which is out of print but you can buy it used. This entire section describes how to do a sleep restriction to get your sleep rhythm back on track. I tried it, too.

For those of use who know for sure they have genuine insomnia, and are sick and tired of being accused of paradoxical insomnia, Espie has a section on this, too. He states that many are, indeed, mistakenly accused of paradoxical insomnia when in fact they really do have insomnia. He shows you a way to measure sleep efficiency and explains the different types of insomnia. Most who insist they have insomnia over a long period, and are truly exhausted and are asking for advice should be taken seriously, not told it is all in their heads!

Some people wake frequently, some cannot fall asleep, some wake early. And for many, a combination of these. Or sleep is not good quality.

I never went to a sleep clinic for fear that I would be misdiagnosed with sleep apnea! It is currently overdiagnosed and I do not have that! I did find out, though.