I always wear my watches to go to sleep, i've done this since i was a child and i used to set the alarm in my Casio Databank to wake up in the morning to go to school and sometimes in the middle of the night i turned the light on that Casio just check if it was time to wake up. Now i wake up in the middle of the night to check the time on my divers, this is the way im used to and it's easier for me than turn the smartphone on in a dark room.