Just reading your link..... I'm one of the ones who fall asleep on the sofa and it's also happened on the bus several times. Even once at the Hair Dressers' when the wife was having her hair done - I slid of the chair and landed on my ass.
About 10pm and I always promise myself that I will read a chapter or listen to the news headlines or do both. Unfortunately I nearly always fall asleep then wake again about midnight thinking its time to get up. (which is usually 6am) even though retired I still keep up the habits of a liftime. I'm not overlooked so sleep with the curtains open and if awake like to watch the stars go round. The only thing that really keeps me awake is the full moon. Regards to all. Noels
Ask this question to a shift worker and the answer could be at anytime of the day or night. I used to be permanently knackered when on nights or early mornings. The only shift where I had a 'normal' sleep was after working the afternoon shift. Thankfully I'm retired now and can go to bed and get up when I want (within reason).