What works, what does not, and what is dangerous. Reviewed by the Scan Dose Research Team.
Effective Dose
Key Finding
PMID
0.3-1mg, 30-60 min before bed
Reduces time to fall asleep by 12-17 minutes. Does NOT improve sleep quality. Lower doses as effective as higher.
PMID: 34048901
200-400mg
Promotes relaxation without sedation. Calms racing mind. No drowsiness. Found in OLLY Sleep (100mg — below effective dose).
PMID: 30580081
200-400mg glycinate or citrate
Improves sleep quality in people with low magnesium. Glycinate form preferred for sleep.
PMID: 33865376
2x 8oz glasses daily
Natural melatonin source. Reduced insomnia severity in older adults.
PMID: 22038497
300-600mg, 30-120 min before bed
Mixed evidence. May take 2-4 weeks. Modest effect if any.
PMID: 16619358
Supplement
Why It Fails
Marketing Claim vs Reality
High-dose melatonin (>5mg)
NOT more effective than 0.3-1mg. More side effects.
Claim: "10mg for deep sleep." Reality: No dose-response above 1mg.
CBD for sleep
Mixed evidence. May help anxiety-related insomnia only.
Claim: "Sleep supplement." Reality: Not proven for primary insomnia.
Antihistamines (Benadryl)
Tolerance builds rapidly. Cognitive impairment.
Claim: "Sleep aid." Reality: Reduces sleep quality. Alzheimer's risk with chronic use.
GABA supplements
Does not cross blood-brain barrier efficiently
Claim: "Calming." Reality: Oral GABA unlikely to reach brain.
Risk
CYP1A2 inhibition → dramatically increased melatonin levels
Worsens morning blood sugar
Increased blood pressure
Additive sedation
Can CAUSE insomnia — take in morning
Can CAUSE insomnia — take in morning
Can CAUSE insomnia — take in morning