It depends on your circumstances, so first you have to identify the cause, but here are a few general pointers:
1. Our circadian/clock rhythm is naturally in-tune with the planetary movement of the Sun. At certain hours of the day, it releases specific chemicals such as melatonin which aid sleep. The introduction of artificial light conflicts with this natural biological process, and so, step one is to slowly reduce screen-time after sunset and ideally replace any harsh LED or fluorescent lights with incandescent/tungsten or candles optimally, which is an organic source of light and mimics the powers of the sun. Also, if possible, try to get AM sun exposure within the first hour of sunrise. This triggers many hormonal effects and chemicals which aid optimal biological function.
2. Personal reccomendation, which aids massively with health: increase your consumption of Magnesium Glycinate. Normally, you'd get this naturally but especially if you live in the city the water is deprived of optimal minerals which aid good sleep, wherein you'd normally get this. Your sleep will instantly improve, and likely experience more vivid dreams. Get some stillwater, Magnesium Glycinate, L-theanine, and Inositol and pour some into your drinking water. Instant results.
3. Are you an introvert? If so, it's likely you're not getting enough social interaction in groups. Introverts gain energy from being alone, so it's possible you have an excess amount of energy. Spending adequate amounts of time interacting with groups throughout the day will exhauast your energy reserves enough throughout the day to fall asleep at night.