Melatonin Receptor Agonist / Chronobiotic Pregnancy: Avoid — no human safety data

Melatonin (Paediatric — Sleep Disorders)

Brand names: Circadin (PR), Slenyto (PR paediatric)

Adult dose

Dose: Insomnia (adults ≥55 years): Circadin 2 mg OD (MR), 30 min before bedtime for up to 13 weeks

Route: Oral

Frequency: Once nightly

Max: 2 mg OD (licensed adults); higher doses off-label

Adult use primarily for circadian rhythm disorders

Paediatric dose

Route: Oral

Frequency: 30–60 min before desired sleep time

Max: 10 mg nightly (in neurodevelopmental conditions)

Concentration: 1 mg, 2 mg, 5 mg tablets; 1.8 mg Slenyto (for ASD/Smith-Magenis) mg/ml

Slenyto (licensed): 2–18 years with ASD or Smith-Magenis syndrome: 1.8 mg at bedtime, increase to 3.6 mg then 7.2 mg if needed. Off-label (ADHD, general sleep disorders): 0.5–5 mg, 30–60 min before sleep. Liquid preparations available (compounded). Circadin not recommended <55 years (licensed); Slenyto for specific conditions.

Dose adjustments

Renal

Caution in renal impairment — limited data

Hepatic

Avoid in hepatic impairment — extensively hepatically metabolised; levels markedly increased

Clinical pearls

Slenyto is the only licensed formulation for paediatric sleep disturbances in ASD/Smith-Magenis — first-line pharmacological option in UK after sleep hygiene/behavioural interventions
NICE NG225: sleep disorders in children with learning disabilities/autism — melatonin after behavioural interventions tried
Good sleep hygiene must be in place before and alongside melatonin — not a substitute for behavioural approaches
Hepatic impairment: levels rise dramatically — virtually avoid in decompensated liver disease

Contraindications

Hepatic impairment
Autoimmune disease (theoretical — melatonin modulates immune system)

Side effects

Somnolence (next morning)
Headache
Dizziness
Enuresis (bedwetting)
Hypothermia
Mood changes

Interactions

CYP1A2 inhibitors (fluvoxamine) — dramatically increase melatonin levels; avoid combination
Caffeine — inhibits melatonin metabolism
Alcohol — may reduce melatonin efficacy
CNS depressants — additive sedation

Monitoring

Sleep diary/actigraphy (response assessment)
Side effects (morning somnolence, enuresis)
Mood and behaviour
Review at 4 weeks and 3-monthly thereafter

Reference: BNF for Children; NICE NG225; Slenyto SPC; Cochrane Review on Melatonin in ASD Sleep. Verify against your local formulary and the latest BNF before prescribing.

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways