I too have hypothyroidism, around the time that was diagnosed, mid 40s, having been completely unaware such a condition existed, I remember feeling unbelievably tired all the time. 20 years on and still experiencing menopausal symptoms, I often fall asleep 9 pm usually when I'm about to watch something worthwhile on tv., occasionally I've also fallen asleep in the afternoon. I find such sleeps simulteanously annoying and satisfying, annoying because of what I've missed but satisfying because afterwards I feel I experience a 2nd wind, although not always a good thing if I'm about to retire to bed.
My husband will often come home in the afternoon from doing something physical, golf or gym, start reading and literally just go, often dropping the book as he does, then he will wake himself up again with a start. I try to pre empt that by removing the book if I'm in the same room. I believe napping is a way of regenerating ourselves, hence the term "power nap" but in the right place of course.
