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Melatonin Receptor Agonist — Hypnotic Pregnancy: Avoid — insufficient data; melatonin influences reproductive function.

Melatonin Modified-Release (Elderly Insomnia)

Brand names: Circadin

Adult dose

Dose: 2 mg modified-release tablet once daily, 1–2 hours before bedtime; take with or after food
Route: Oral
Frequency: Once daily at bedtime
Max: 2 mg/day
Licensed in UK for short-term treatment (up to 13 weeks) of insomnia in adults ≥55 years — replacement of declining endogenous melatonin. Non-addictive, no dependence or next-day hangover. NICE TA739 (2021) recommended as first-line pharmacological option for insomnia in adults ≥55 years. Modified-release formulation mimics physiological melatonin rise.

Paediatric dose

Route:
Circadin not licensed in children. Melatonin is used off-label in paediatric insomnia (autism spectrum disorder, ADHD, neurodevelopmental conditions) — specialist paediatric guidance required. Slenyto (prolonged-release) is licensed for children 2–18 years with ASD or Smith-Magenis syndrome.

Dose adjustments

Renal

Use with caution in severe renal impairment — no specific dose adjustment but limited data.

Hepatic

Avoid in hepatic impairment — increased melatonin levels due to reduced first-pass metabolism; risk of excessive drowsiness.

Clinical pearls

  • NICE TA739 (2021): melatonin 2 mg MR recommended as first-line pharmacological option for insomnia in adults ≥55 — preferred over benzodiazepines and Z-drugs which carry falls, dependence, and cognitive impairment risks in elderly. Cost-effective at current NHS price
  • Endogenous melatonin decline: melatonin levels fall approximately 80% from age 20 to 70 — circadian rhythm disruption contributes to insomnia and sleep fragmentation in elderly. MR Circadin provides physiological replacement over 8–10 hours
  • Non-pharmacological approach first: sleep hygiene education, CBT for insomnia (CBT-I) is the gold standard for chronic insomnia — all patients should be offered or referred for CBT-I. Melatonin is the preferred pharmacological adjunct when CBT-I is insufficient or not available
  • Comparison with Z-drugs (zopiclone/zolpidem): melatonin has no rebound insomnia, no hangover effect, no dependence, no cognitive impairment — substantially safer profile for elderly patients. AGS Beers Criteria 2023: Z-drugs listed as potentially inappropriate in older adults

Contraindications

  • Hepatic impairment (relative — accumulation)
  • Autoimmune conditions (theoretical concern — limited evidence)

Side effects

  • Headache (most common — 3–10%)
  • Drowsiness (next day — less than benzodiazepines)
  • Dizziness
  • Irritability
  • Vivid dreams
  • Mild hypotensive effect (use with caution in hypotensive elderly)

Interactions

  • Fluvoxamine (strong CYP1A2 inhibitor — dramatically increases melatonin levels 17-fold; avoid combination)
  • Ciprofloxacin (CYP1A2 inhibitor — increases melatonin levels; monitor for excessive sedation)
  • Rifampicin (CYP1A2 inducer — reduces melatonin levels; reduced efficacy)
  • Anticoagulants (warfarin — occasional interaction reports; monitor INR)

Monitoring

  • Sleep diary (latency, duration, quality) — efficacy assessment
  • Daytime functioning and alertness
  • Blood pressure (mild hypotensive effect in some patients)
  • LFTs if prolonged use beyond 13 weeks (off-label)

Reference: BNFc; BNF 90; NICE TA739 (Melatonin for Insomnia 2021); Circadin SPC; Leger et al. BMJ 2004; AGS Beers Criteria 2023; STOPP/START v3. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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