What over‑the‑counter (OTC) supplement(s) can be recommended for a healthy adult with anxiety‑related difficulty falling asleep?

OTC Supplement Recommendation for Anxiety and Sleep Onset Difficulties

For a healthy adult with anxiety-related difficulty falling asleep, melatonin (specifically prolonged-release formulation) is the most evidence-based OTC supplement, though the American Academy of Sleep Medicine explicitly advises against using OTC supplements as first-line treatment and instead recommends Cognitive Behavioral Therapy for Insomnia (CBT-I). 1, 2

Critical Context: Guidelines Recommend Against OTC Supplements as First-Line

• The American Academy of Sleep Medicine does not recommend over-the-counter antihistamines, melatonin, antipsychotics, or traditional benzodiazepines as first-line treatments due to lack of efficacy, risks, or higher risk profiles. 1
• The American College of Physicians strongly recommends that all patients with stress-induced insomnia should receive CBT-I as initial therapy, based on moderate-quality evidence showing sustained benefits for up to 2 years without the risks of tolerance, dependence, or adverse effects associated with medications. 1
• CBT-I demonstrates superior long-term efficacy compared to all pharmacologic treatments and should be started before or alongside any medication. 3

If You Still Want an OTC Supplement: Best Evidence

Melatonin (Prolonged-Release)

• Among OTC supplements, prolonged-release melatonin formulations in adults with diagnosed insomnia demonstrated the most consistent beneficial effects (versus placebo) on sleep measures, specifically sleep onset and sleep quality, with favorable tolerability. 4
• Melatonin and valerian have substantial evidence to demonstrate their effectiveness and safety among the most studied OTC products for insomnia. 5
• Immediate-release melatonin showed limited beneficial effects compared to prolonged-release formulations. 4

Practical dosing: Standard OTC melatonin doses range from 0.5-5 mg taken 30-60 minutes before bedtime, though optimal dosing remains unestablished. 6

Valerian (Second Option)

• Valerian shows promising but inconclusive findings in alleviating insomnia symptoms in adults, with most studies demonstrating positive effects on insomnia symptoms. 5
• However, clinical trial data for valerian suggested limited beneficial effects in randomized controlled studies over the past 12 years, lacking robust clinical evidence supporting efficacy and safety. 4
• Valerian may be effective in improving sleep quality and reducing insomnia symptoms through modulation of neurotransmitter systems and regulation of sleep-wake cycles, though the strength of evidence varies with unestablished optimal dosages, formulations, and treatment durations. 6

Magnesium (Third Option)

• Magnesium is one of the more widely researched supplements for sleep quality, though studies have conflicting results. 7
• Evidence supporting magnesium for sleep improvements is less robust than melatonin. 7

Supplements to Avoid

Diphenhydramine and Doxylamine (Antihistamines)

• Over-the-counter antihistamines such as diphenhydramine and doxylamine are not recommended due to lack of efficacy data, daytime sedation, confusion, urinary retention, and tolerance development. 2
• Clinical trial data for diphenhydramine lacks robust clinical evidence supporting efficacy and safety. 4

Other Supplements with Insufficient Evidence

• Zinc, vitamin D, and L-theanine are less supported by clinical evidence for sleep improvements. 7
• Nitrates have limited research supporting their use for sleep quality. 7

Critical Caveats

• The quality and purity of supplements vary widely due to a lack of strict regulations, which poses safety concerns. 6
• Supplements are not without risks, such as rare but serious adverse effects and potential interactions with prescription medications. 6
• Larger, well-designed clinical trials are needed to establish the efficacy and safety of these supplements for clinical decision-making. 6

Addressing the Anxiety Component

• Cannabidiol (CBD) showed anxiety scores decreased within the first month in 79.2% of patients (57 of 72 adults) and remained decreased during the study duration, though sleep scores fluctuated over time. 8
• CBD was well tolerated in all but 3 patients in this large case series, though controlled clinical studies are needed. 8
• Evidence points toward a calming effect for CBD in the central nervous system, with preclinical and clinical evidence documenting value in some neuropsychiatric disorders including anxiety. 8

Bottom Line Algorithm

If refusing CBT-I and insisting on OTC supplement:

1. Try prolonged-release melatonin first (0.5-5 mg, 30-60 minutes before bed) for sleep onset difficulties 4, 5
2. Consider valerian as second option if melatonin ineffective after 1-2 weeks 5
3. Avoid antihistamines completely (diphenhydramine, doxylamine) 2, 4
4. For anxiety component specifically, consider CBD though evidence is preliminary 8
5. Reassess after 2-4 weeks and strongly reconsider CBT-I if no improvement 1