Health Library · Medications

Melatonin side effects and safety

Overview

Melatonin is a hormone that regulates the sleep-wake cycle. As a supplement it works as a chronobiotic — helping shift sleep timing — better than as a straight sedative.

Symptoms to watch for

  • Morning grogginess (dose too high)
  • Vivid dreams or nightmares
  • Headache
  • Mild GI upset

Treatment

Low dose (0.3–3 mg) taken 1–2 hours before target bedtime. Higher doses aren't better and can cause morning hangover. Supplement quality varies — look for USP verified.

When to book a visit

Book if you have persistent sleep problems — CBT-I outperforms any supplement long-term.

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