Melatonin

What is Melatonin?

Melatonin (N-acetyl-5-methoxytryptamine) is a naturally occurring hormone produced primarily by the pineal gland in the brain. This neurohormone plays a crucial role in regulating the body’s circadian rhythm, or internal biological clock, which controls sleep-wake cycles. Melatonin production typically increases in darkness and decreases with light exposure, signaling to the body when it’s time to sleep.

As a dietary supplement, melatonin is widely used to address sleep disorders and circadian rhythm disruptions. Unlike many hormones, melatonin is available over-the-counter in most countries and is considered relatively safe for short-term use in healthy adults.

Health benefits & uses

Strong evidence:

• Jet lag: Clinical studies consistently show melatonin effectively reduces jet lag symptoms when taken at appropriate times relative to the destination time zone
• Delayed sleep phase disorder: Well-established benefit for individuals whose natural sleep-wake cycle is significantly delayed compared to conventional schedules

Moderate evidence:

• Insomnia in older adults: Research indicates melatonin can improve sleep onset time and quality, particularly in individuals over 55 whose natural melatonin production has declined
• Shift work sleep disorder: May help workers adapt to non-traditional schedules, though timing of administration is critical

Limited evidence:

• General insomnia: Mixed results for primary insomnia in younger adults without underlying circadian rhythm disorders
• Seasonal affective disorder: Some studies suggest potential benefits, but more research is needed
• Antioxidant effects: Preliminary research suggests melatonin may have neuroprotective properties, but clinical significance remains unclear

How it works

Melatonin functions by binding to melatonin receptors (MT1 and MT2) in the brain, particularly in the suprachiasmatic nucleus, which serves as the body’s master circadian clock. When melatonin levels rise in the evening, it signals the brain to prepare for sleep by lowering body temperature, reducing alertness, and promoting drowsiness.

The hormone also influences the release of other sleep-related neurotransmitters and hormones, including GABA and growth hormone. Additionally, melatonin exhibits antioxidant properties, potentially protecting cells from oxidative damage, though this mechanism’s clinical relevance for supplementation remains under investigation.

Dosage

There is no established Recommended Dietary Allowance (RDA) or Tolerable Upper Intake Level (UL) for melatonin, as it’s considered a hormone rather than an essential nutrient. Typical dosing recommendations include:

• For jet lag: 0.5-3 mg taken 30 minutes before desired bedtime at destination, starting on arrival day
• For sleep disorders: 1-3 mg taken 1-2 hours before intended sleep time
• For delayed sleep phase: 0.5-3 mg taken 2-3 hours before desired sleep onset

Lower doses (0.3-1 mg) may be as effective as higher doses and cause fewer side effects. Extended-release formulations may benefit individuals who experience early morning awakening. Always consult a healthcare provider before beginning melatonin supplementation, especially for chronic use or underlying sleep disorders.

Food sources

While the body produces melatonin naturally, small amounts are found in certain foods:

• Tart cherries and cherry juice (highest natural source)
• Grapes and grape products
• Tomatoes
• Walnuts and pistachios
• Oats and barley
• Milk (particularly from night-milked cows)

However, food sources contain relatively low concentrations compared to supplements and are unlikely to provide therapeutic effects for sleep disorders.

Safety & side effects

Melatonin is generally well-tolerated for short-term use. Common mild side effects may include:

• Daytime drowsiness or grogginess
• Headache
• Dizziness
• Nausea
• Vivid dreams or nightmares

Long-term safety data is limited. Some concerns include potential suppression of natural melatonin production with prolonged use, though this appears reversible. Quality control varies among over-the-counter products, with some studies finding significant variations in melatonin content compared to label claims.

Interactions

Drug interactions:

• Blood thinners (warfarin): May increase bleeding risk
• Sedatives and sleep medications: May enhance drowsiness effects
• Blood pressure medications: May affect blood pressure regulation
• Diabetes medications: May influence blood glucose levels
• Immunosuppressants: May interfere with immune-suppressing effects

Supplement interactions: Limited evidence for significant interactions with other supplements, though combining with other sedating herbs or supplements may enhance drowsiness effects.

Who should be cautious

• Pregnant or breastfeeding women: Safety not established; avoid use
• Children: Should only be used under medical supervision
• Individuals with autoimmune disorders: May stimulate immune system activity
• People with seizure disorders: May lower seizure threshold
• Those with depression: May worsen symptoms in some individuals
• Individuals taking multiple medications: Require medical consultation due to potential interactions

Frequently asked questions

Can I take melatonin every night?

While melatonin appears safe for short-term nightly use (up to several weeks), long-term daily use should be supervised by a healthcare provider. Some experts recommend taking periodic breaks to prevent potential tolerance or suppression of natural melatonin production.

Why do I feel groggy the morning after taking melatonin?

Morning grogginess may result from taking too high a dose, taking it too late in the evening, or using extended-release formulations when immediate-release would be more appropriate. Try reducing the dose or taking it earlier in the evening.

Is melatonin addictive?

Melatonin is not considered physically addictive and doesn’t produce withdrawal symptoms when discontinued. However, some people may develop psychological dependence on sleep aids in general.

Can melatonin help with anxiety?

While melatonin may indirectly help anxiety related to sleep difficulties, it’s not primarily an anti-anxiety treatment. Some studies suggest modest anxiolytic effects, but other treatments are more appropriate for anxiety disorders.

How long does it take for melatonin to work?

Immediate-release melatonin typically begins working within 30-60 minutes. For optimal effectiveness, timing is crucial—take it 1-2 hours before your desired sleep time, not when you’re already in bed trying to fall asleep.

References

This profile is based on peer-reviewed research and clinical guidelines. Individual responses to supplementation may vary, and this information should not replace professional medical advice.