Hi Friend2U,
I have heard of many PWMS that stay up late and get up late. I know my circadian rhythm is turned around, or broken (sigh). I can go to bed late and wake up late, and get a good night's sleep, much better than when I try for an earlier bedtime.
I do miss the mornings. If I have an early appointment, I end up with very little sleep when the alarm goes off. I have tried to turn myself around but to no avail.
I do find while up at night I "notice" more of the aches, pain and sensations more. Like the MS hug starts getting bad around 10 pm. I try to be on the net or just read a book until I'm tired enough to conk-out.
I think Karousel is right, less distractions at night. Too much peace and quiet, and you think of your pain or symptoms more. It makes them magnify out of portion to the day. JMO
I do exercise a bit and stretch like Sally said, to try to work out the stiffness. I don't know if it is all muscles spasms, or age related with me. I wake up with tightness, that takes an hour to loosen up. I sit and have coffee, then move, then sit and then move again.
If you are not as active in the evening, as the daytime, I think that has a lot to do with it. If you're worn out from the day, exhaustion does it too. I wish I knew.
What do you think might me the answer Freinds2U? It could benefit a lot of us.

Maybe we need to work the night shift, ya think?