Sleep cycle peculiarities.

This winter, I've noticed peculiarities in my sleep cycle, or at least aspects of it that I've never noticed before.

In particular, I seem to have very very heavy sleep in the last hour or two right before I wake up.

I've noticed this because I've had a hard time getting out of bed from tiredness an inordinate amount this winter, but a handful of times the kids upstairs were noisy or I needed to take a piss like 3-4 hours before I was due to get up, and I wasn't particularly groggy at that point when I got up, but I totally was when I tried to make myself get up the final time for the day.

As best I can figure it, those two different times of coming into wakingness came at different points in my sleep cycle, the first point of time when it was easier for me to get up, the second when it was much more difficult for me to do so.