Consider checking your D3 vitamin metabolite levels in blood. I had trouble falling asleep, had single digits of 25(OH) D3 concentration (The norm is 20+ ng/ml).

For now I was prescribed 20k IU of vitamin D3 twice a week. Other things that helped - no caffeine after 3-4 pm and a cup of raspberry-hibiscus tea in the evening (It's very relaxing).