The supplement aisle at any pharmacy contains melatonin in doses ranging from 0.3mg to 20mg. This proliferation of melatonin products reflects both its popularity as a sleep aid and a widespread misunderstanding of what melatonin actually does. Taking melatonin to fall asleep is roughly like taking a sunrise photograph to make the sun rise earlier—helpful in some circumstances, but fundamentally misunderstood by most users. Melatonin is a hormone produced by the pineal gland in response to darkness signals from your retinohypothalamic tract. Its primary function isn't to induce sleepiness directly but to signal to cells throughout your body that darkness has arrived. Think of melatonin as a broadcast announcement: "Attention all systems: nighttime is here." Different tissues receive this signal differently, but the overall effect is metabolic slowing and preparation for sleep. The suprachiasmatic nucleus (SCN) uses melatonin onset timing to calibrate your circadian clock. Melatonin typically begins rising 2-3 hours before your natural sleep onset, creating a gradual transition from daytime metabolism to nighttime metabolism. This rise is suppressed by light exposure, which is why bright evening light delays melatonin onset and pushes your circadian rhythm later. Dim, warm light in the evening allows melatonin to rise on schedule. Supplemental melatonin dosing confuses this natural timing system. The pills flood your bloodstream with melatonin all at once, rather than the gradual rise your body produces naturally. Research suggests that extremely low doses (0.3mg or less) may more closely mimic physiological levels, while higher doses create artificial melatonin peaks that don't necessarily improve sleep and may cause next-day grogginess through prolonged elevation. The evidence for melatonin supplementation is strongest for circadian rhythm disorders: jet lag, shift work adjustment, and irregular sleep-wake schedules. In these cases, melatonin helps reset the circadian clock toward target timing. For general insomnia without circadian component, evidence is weaker, and behavioral interventions typically outperform melatonin supplementation. Melatonin production declines with age. Children and young adults produce abundant melatonin; older adults often produce considerably less. This decline correlates with increasing sleep difficulties in older populations, suggesting that melatonin supplementation might address age-related sleep changes. However, research results are mixed, and supplementation isn't uniformly effective for older adults. The practical takeaway: melatonin isn't a sleeping pill. It's most useful as a circadian adjustment tool when used at specific times in low doses. Taking melatonin at high doses randomly in the evening may produce some sleep benefits, but suboptimal timing can actually worsen circadian alignment. If you use melatonin, timing the dose appropriately (typically 2-3 hours before desired sleep onset) matters more than the dose itself. Beyond supplementation, anything that supports natural melatonin production indirectly improves sleep. Limiting evening light, particularly blue wavelengths, allows your pineal gland to produce melatonin on schedule. Getting morning light exposure anchors circadian timing so evening melatonin onset occurs consistently. These behavioral interventions address the root causes that melatonin supplementation attempts to treat symptomatically.