Personally, I sleep 7.5 hours per night. 5 cycles of one and a half hours. I try to go to bed at 10:00 pm and wake up at 5:30 am. You will rarely see (in normal times) a 50-year-old person sleeping until noon, nor a student getting up at six in the morning on weekends. I think it’s a question of internal clock, which must also be due to age. The more years go by, the more we feel the need to accomplish things… It’s a small sense of urgency that animates people as they age. I am 58 years young.