Second Sleep

The most beautiful, relaxing, restful sleep I ever get is what I call "second sleep."*

My basic definition of "second sleep" is that you go to bed, fall fully asleep, awake fully to the extent that it would be plausible to just begin your day at that point (so excluding, e.g., waking up in the middle of the night to go to the bathroom), but volitionally electing to go back to sleep anyway. That latter phase is "second sleep".

To take a recent example, I went to bed at a normal time for me (about 1 AM), but woke up at 8:30 AM because I had a morning Zoom call. After the call was over (around 9:30 AM), I realized I had nothing else scheduled for the day, so I affirmatively crawled back to bed and went back to sleep ... and stayed asleep until 2:30 PM. And it was glorious.

Do others relate to this? Sometimes I think I like it so much I actually don't mind if I accidentally leave on my alarm and wake myself earlier than I have to, because the joy of falling back asleep is so nice. Same when I'm sick -- a fitful night of sleep where I find myself lying awake at 6 AM can be entirely salvaged if I can fall asleep then, because at that point I'll get a full "night" of second sleep and feel great about it.

* This seems potentially related to but also distinct from the pre-modern practice of biphasic sleep, mostly because for me it's typically time-shifted much later. As it happens, if I do go to bed around 10 PM I do exhibit a "biphasic" pattern -- I typically wake around 2 AM, and can't fall back asleep for a few hours -- but for me that is a miserable experience rather than a restful one.