It might be tempting to pop another melatonin when you want to fall asleep fast, but Shelby Harris, PsyD, DBSM, a behavioral sleep doctor and author of The Women’s Guide to Overcoming Insomnia, previously told mbg that melatonin is best consumed in low doses (0.5 milligram to 1 milligram).

“If you’re taking more than 3 to 5 milligrams nightly, then melatonin isn’t likely for you. There’s just no data suggesting that more than [0.5 milligram to 1 milligram] is indicated for sleep issues, and sometimes more is just more,” she explains. On top of that, mbg’s vice president of scientific affairs Ashley Jordan Ferira, Ph.D., RDN, adds that “Taking melatonin, particularly at higher doses, can be linked to undesirable desensitizing phenomena, such as nightmares, grogginess, and headaches.”