Caffeine has a half-life of about five to six hours. A 4pm coffee still has half its caffeine in you at 10pm. In one controlled study, caffeine taken six hours before bed cut measured sleep by about an hour, and people didn't notice the loss. Evidence: decent
You can "fall asleep fine" on late caffeine and still get worse sleep. The damage is to depth, not to falling asleep.
Same theme: Before bed
Before bed
Alcohol is not a sleep aid
If you drink, stop three hours before bed. On a bad-sleep week, none.
no timeEvidence: solid
Before bed
Cool the bedroom
Tonight, turn the bedroom heating down or open the window before bed. Cool room, warm covers.
no timeEvidence: decent
Before bed
Melatonin is modest, not magic
Before you try melatonin, keep one wake-up time and get morning daylight for a week. If you still want it, ask a pharmacist or doctor first.
no timeEvidence: decent