Melatonin

Melatonin is the most misunderstood sleep aid on the market because it is sold and consumed as if it were a sedative like diphenhydramine or zolpidem. It is not. Melatonin is a chronobiotic hormone — its primary function is to signal “nighttime” to the brain’s master clock, not to knock you out. This distinction explains why 10mg tablets produce grogginess and headaches while 0.3mg properly timed can reset a delayed sleep schedule.

The mechanism is circadian, not hypnotic. The pineal gland releases melatonin in response to darkness, peaking around 2-4 AM in a typical sleep-wake cycle. Melatonin activates MT1 receptors in the suprachiasmatic nucleus to reduce neuronal firing and promote sleep readiness, and MT2 receptors to shift the timing of the circadian clock itself. The hormone’s effect is on timing and phase — when you take it matters far more than how much you take.

The evidence for dose is counterintuitive. Buscemi et al. (2005) meta-analyzed primary sleep disorder trials and found melatonin reduced sleep onset latency by a modest but real 11.7 minutes and increased total sleep time by 18.8 minutes. More importantly, physiological doses (0.3-0.5mg) produce plasma concentrations matching natural nighttime peaks (~500-1,000 pg/mL). Pharmacological doses (3-10mg) produce levels 10-20x higher, which can cause next-day grogginess, vivid dreams, headaches, and paradoxically worsen sleep architecture in some individuals.

For delayed sleep phase syndrome (DSPS), the evidence supports a specific protocol: 0.3-0.5mg taken 4-5 hours before the individual’s dim-light melatonin onset — typically late afternoon or early evening for someone who naturally falls asleep at 2 AM. This low dose, precisely timed, advances the circadian phase by 30-60 minutes per day. High doses taken at bedtime often fail because they either miss the phase-advancement window or cause receptor desensitization.

For jet lag, the evidence is strongest. Herxheimer and Petrie (2002) Cochrane meta-analysis of 10 trials found melatonin remarkably effective for eastward travel across five or more time zones, with few side effects. The protocol: take at destination bedtime for 2-5 nights after arrival. Westward travel benefits less because the circadian system naturally delays more easily than it advances.

The honest framing: melatonin is not a sleeping pill for chronic insomnia. Cognitive behavioral therapy for insomnia (CBT-I) has stronger and more durable evidence. Melatonin is a tool for circadian realignment — jet lag, shift work, DSPS — and works best at low doses with precise timing. The supplement industry’s standard 3-10mg tablets are pharmacologically excessive for most applications.

Practical guidance: for DSPS, 0.3-0.5mg at 4-5 hours before desired bedtime, taken consistently for 2-4 weeks. For jet lag, 0.5-5mg at destination bedtime for 2-5 nights. For general sleep onset, 0.5-1mg 30-60 minutes before bed. Avoid if pregnant, on fluvoxamine, or with autoimmune conditions. Use time-release formulations if nighttime awakening is the primary issue.