My wife and I, both in our mid-70s, both suffer from insomnia. She goes to bed early and is awake for two or three hours in the middle of the night, when she reads herself back to sleep. I take one "sleep-aid", the night after two successive disturbed nights.
I used to have a nap of an hour or two most afternoons, but then I discovered (I forget how!) that eating bread is what caused me to doze off. So I cut bread out of my diet altogether. Now, the only time I need to nap is when I've over-eaten. I have to discipline myself to stop eating before I'm full.
I hope this discovery is useful to someone else here.