[redcalx]

I find if I'm working on a difficult problem, I feel like I can make more rapid progress if I take a 'nap' early afternoon in that post lunch drowsy period. I often start thinking about the problems again immediately on waking, and typically find that is the most productive period in terms of breakthroughs and making mental connections.

I put 'nap' in quotes because I don't set an alarm (unless there is specific need to), and for me that usually means a 2 hour sleep! I figure that is made up of 90 mins of one sleep cycle, and some time either side for falling asleep and waking.

https://en.wikipedia.org/wiki/Sleep_cycle

All made possible by pandemic working from home.

[singingfish]

45 minutes is a good period as it gets you to the beginning of your REM cycle. I often aim for 45 minutes as a nap, but for reasons I don't understand, 20 minutes can be disproportionately invigorating.

[redcalx]

As I understand it REM sleep is at the start and end of each cycle, thus 45 mins would put you squarely in a deep non-REM phase. That said, the cycles get progressively shorter in an overnight sleep, so it's possible a daytime nap sleep cycle would be much shorter than the full 90 mins.

[m463]

If I don't set an alarm, my head feels like cement afterwards.

[ford_o]

Do you still sleep 8 hours at night?

[redcalx]

This is anecdata, but I don't think it affects my overnight sleep if my nap is post lunch, although it definitely does if I sleep later in the day, say from 4pm to 6pm. I think there's enough time and mental exertion in the afternoon and evening that I sleep normally overnight. Possibly it's a slightly shorter sleep overnight, but a net increase per day overall, or, at least no shorter overall.