Sleep is a completely personal or idiopathic need. I have looked into this many, many times over the years because I have suffered sleep disturbance since my twenties. At sixty five I would guess that your need for sleep is slowly diminishing but we are all so different that what is great for one person is unmanageable for another. I am afraid it is a case of trial and error. All the old adages apply, avoid caffeine later in the day, no tech/devices such as TV, radio etc in the bedroom.
Michael Mosley made a BBC programme on sleep not so long ago, perhaps you could do a search on iplayer or youtube for it. For me sleeping in a cool bedroom helps especially after a hot shower. I read a little and try not to think of problems while trying to get to sleep. Eight or nine hours is enough for me if it is unbroken.