It takes the average human about 15 minutes to fall asleep.
To wake up refreshed at 3:50 AM, You should try to sleep at one of the following times:
A good night's sleep consists of 5 to 6 sleep cycles that are in 90 minutes. Waking up during deep sleep will make you feel groggy.
If you have trouble falling asleep, try getting some sunlight. Sunlight helps the body's internal biological clock reset itself each day. Sleep experts recommend exposure to an hour of morning sunlight for people having problems falling asleep.