A few thoughts while I was trying to sleep last night.
Nocturia. The need to get up and pee. Easily resolved. Don't drink anything the night before then have a paracetemol when you get up to get rid of your dehydration headache and three mugs of coffee/tea.
I stayed in England recently and couldn't believe the light pollution even with curtains closed. Bearing in mind our bodies wake up with light, if your bedroom is light that cannot help no matter what you have become used to. You can get blackout blinds.
Stress and activity. Most folk lead fairly stressful lives. Some of it is good but then slump in front of Tv and watch something stressful- Drama or a film. Then go to bed expecting to come down from that high and pop off to sleep. I suspect in an ideal world you would watch the film, then go out for an hours walk with the dog, come back sit and have a chat, then go to bed.
Food and drink. More bad practices. It is tempting to throw down loads of food and drink late in the day to assuage the rigours of the day and because you have earnt it. Problem is that causes your body to work overtime and heats you up. That makes you hot in bed.
Bedroom ambient temp. I think modern houses are far too hot in the bedroom. Again we treat ourselves because we can/or deserve it.
Beds. I agree with Dr Gixer. Memory foam mattresses and pillows are the best thing since sliced bread. I haven't tried a water bed .
Power naps. (In Spain we would call that a siesta). I have quite a few friends in Britain who admit to power naps in the afternoon. Not easy if you have a job. Again that is how nature designed our bodies. It is we that impose the "eight hours sleep at night" on our bodies.