It is important to understand one's sleep style. Early birds and night owls are genetically predisposed to these traits. Normal wake and sleep times can only be adjusted an hour or so. It makes late shift work all but impossible. The key component is wake time. It should be consistent day to day, 6:00 am to 8:00 am or so. This sets up the sleep system to start to be ready for sleep 12 to 14 hours later.

If you struggle to fall asleep at night, try waking up earlier. Stop all active cognitive efforts and activities 2 hours before your hoped sleep time. Passive activities can help the brain settle down. Many can be sleepy but alert. Set up your sleep environment so you do not have to do anything when that sense of sleepiness happens except turn off a light or two and climb into bed.

If you have a project you were working on cognitively in the evening, make notes of your stopping point with comments about the next step for the next day. In other words, do not take cognitive tasks to bed.

I watch TV shows that I can turn off at any time. Nothing important or that creates a sense of "What comes next?" Reruns are good for this.

If there is a metabolic issue like thyroid, it should be addressed. If a 50 mgs or 100 mgs of 5-HTP helps with serotonin, then use it. For most, it is just poor sleep planning and anxiety or cognitive stimulation.

Do not nap during the day. It resets to sleepiness timer.