MELATONIN & SLEEP: SCIENCE-BACKED, PLAIN-LANGUAGE GUIDE “Onset depends on formulation, dose, and your internal clock.” Time to feel sleepy after melatonin varies. In practice, immediate-release melatonin may help sleep onset within about 30–60 minutes for some people, while others may need 90–120 minutes. Timing is the biggest variable: taken close to your biological night it’s more effective; taken too early, too late, or during the day it may be weaker or counterproductive. Bright evening light (screens), caffeine, heavy meals, and high stress can blunt melatonin’s effect. So evaluate melatonin alongside light reduction, a calming routine, and consistent sleep timing. For jet lag or delayed sleep phase, the goal is often shifting the clock rather than instant sedation—sleepiness may not appear immediately on day one, but the schedule can realign over several days. If there’s no meaningful benefit after 1–2 weeks of correct use, reassess the plan and underlying causes rather than simply increasing the dose.