“Melatonin is a hormone that the pineal gland in our brains makes in response to dim light,” Wermter explains. “[It] helps regulate our circadian rhythm by signaling that soon it will be time for sleep.” Taking extra, supplemental melatonin can strengthen the signal that bedtime is here.
However, if you still have excess melatonin in your system by the time you wake up, you’re likely to feel a little groggy and sleepy.
This is bound to happen after you take melatonin doses that are too high, explains leading sleep specialist Michael J. Breus, Ph.D. While melatonin is generally recognized as safe up to 10 milligrams, Breus says that more is not better when it comes to supplementing with the hormone, unless otherwise instructed by a doctor.
Even doses in the 1- to 5-milligram range can lead to blood serum levels 10 to 100 times higher than what our body makes naturally, Wermter points out. So taking around 0.5 milligrams of melatonin should still be enough to help regulate the circadian rhythm–without causing as much grogginess or morning fatigue.
Laura Erlich, LAc, FABORM, a fertility and obstetric specialist and founder of Mother Nurture Wellness, adds that taking melatonin too close to your desired bedtime can also set you up for fogginess. Consuming supplemental melatonin at least an hour before bed (or 12 hours after you wake up) should minimize the chance of it still being in your system by your morning alarm, says Wermter.
Finally, Christina Graham, R.N., a registered nurse and Noom coach, notes that genetics can also affect how quickly you process melatonin and therefore how your body reacts to it.