I can very easily sleep in the day with no problems, for up to two hours, and even then I could sleep more but I know I shouldn't as I have things to do.
But at night it's nearly impossible to switch my brain off and get to sleep. My body temperature goes up and my limbs ache, and the pillows seem uncomfortable (not like in the day, when my pillows are like luxuriously comfortable). My body temperature even goes down in the day, making me sleep better.
And no, the answer isn't "you can't sleep at night because you sleep during the day", because even if I don't sleep during the day I still can't settle down at night.
Perhaps natural daylight makes me sleepier or something?
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Female