To sleep, perchance to dream

I can't understand why so many people say that as they get older, they need less sleep. With me it seems to be the other way round. Before I retired, I worked in London and would leave home each morning at 6.00, which meant getting up soon after 5.00 if I was to have any breakfast as well as a shower, although I suppose that "soon after 5.00" became 5.20-ish on fairly frequent occasions. But the alarm clock was set to go off at 5.00. At the other end of the day it was quite normal for me to go to bed at about 11.00 so a full night's sleep during the week was about six hours. Admittedly, I was able to catch more on the train to London, but that was little more than cat-napping. Now I'm retired, I am usually in bed by about 11.30pm, and I still need an alarm clock to wake me, but it's now set (normally) for 7.00, although the snooze button gets pressed two or three times after that. The snooze button gives me another nine minutes, which seems to me an odd sort of time lag. Why not a nice, round ten minutes? I suppose that's just another of life's puzzles to which I shall never know the answer.