Like several others, having children made my sleep pattern very different. I always slept with "one ear open" listening for them, for many years. This started from the first days of bringing the babies home from hospital.
We had two under 2s and our DS was badly asthmatic so that added to the need for vigilance. Having had to call the GP in the middle of the night (those were the days - he came without question) made for extreme caution for several years.
Listening for teenagers coming in late, but safe, getting up early to travel to work, often some distance, my own asthma, all made sleeping nothing like the the wonderful deep sleeps I had as a teenager.
That seemed to instil the pattern for very light sleeping, which has continued to this day. Not helped by arthritic flare ups which do often disturb me with pain.
That aside, I now seem to have a night of two halves, which I understand is historically how humans used to sleep. I go to sleep with no problem, unless I am stressed, but waken between 2am and 3am every night. Quite wakeful for an hour then drift back to doze or sleep, if I'm lucky till somewhere between 5am and 6am.
I seem to average 6 or 7 hours and manage on that, with no daytime naps. I have read that older people don't need as much sleep but have also read that shortage of sleep can be a contributory factor in dementia.