National Sleep Foundation

Chapter 2: Insomnia

Pharmacology - OTC

Over-the-Counter Medications

Over-the-counter (OTC) medications are often used to treat insomnia, including: antihistamines, melatonin, L-tryptophan, and herbal treatments. Each is described in more detail blow.

Antihistamines

Antihistamines (e.g., diphenhydramine) are the most commonly used OTC treatment for insomnia.1 Clinical trials indicate that the use of antihistamines for insomnia improved sleep efficiency and decreased insomnia severity in adult participants.2

Side effects of antihistamine use for insomnia include daytime sedation, dizziness, psychomotor impairment, dry mouth, blurred vision, constipation weight gain, and urinary retention.3 Tolerance to the sedative effects of diphenhydramine may develop rapidly, usually within three days.

Melatonin

Melatonin is a hormone secreted by the pineal gland at levels that peak at night between 2:00 and 4:00 AM, and drop before dawn. The circadian-phase altering effects of melatonin make it useful in treating circadian rhythm sleep disorders (see Chapter 5). Melatonin is available as a food supplement in health food stores.

Its efficacy for patients with insomnia is unclear and may depend on drug dose and formulation, as well as the timing, frequency, and duration of administration.4 Endogenous melatonin secretion decreases with age and its use as a hypnotic may be most effective in the elderly.

Research on use of melatonin for patients with insomnia report that it has a positive impact on sleep onset (depending on dose and duration of administration) than on the ability to stay asleep or the length of time spent sleeping. No substantive risks from melatonin use have been reported; the most common side effect is experiencing a headache.5

L-tryptophan

Evidence suggests that L-tryptophan improves sleep in patients with insomnia. There is little research regarding its efficacy in the treatment of insomnia, however. Although L-tryptophan is no longer sold in the U.S., one of its intermediate metabolites (5-hydroxy-tryptophan) is currently still available.

Herbal Treatments

A number of herbal treatments are used to treat insomnia, including valerian root, chamomile, primrose, and passion flower. There is a lack of scientific evidence regarding the efficacy and safety of these treatments, however.

While a few studies have reported some beneficial effect on sleep, most placebo-controlled studies have not demonstrated that herbal treatments demonstrate any improvements in sleep, when compared to placebo.

References

  1. Buysse D, “Clinical Pharmacology of Other Drugs Used as Hypnotics,” In Kryger M, Roth T, Dement WC (eds.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, pages 492-509.
  2. Buysse D, “Clinical Pharmacology of Other Drugs Used as Hypnotics,” In Kryger M, Roth T, Dement WC (eds.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, pages 492-509.
  3. Krystal A, “Pharmacologic Treatment: Other Medications,” In Kryger M, Roth T, Dement WC (eds.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, pages 916-930.
  4. Krystal A, “Pharmacologic Treatment: Other Medications,” In Kryger M, Roth T, Dement WC (eds.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, pages 916-930.
  5. Krystal A, “Pharmacologic Treatment: Other Medications,” In Kryger M, Roth T, Dement WC (eds.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, pages 916-930.
  6. Krystal A, “Pharmacologic Treatment: Other Medications,” In Kryger M, Roth T, Dement WC (eds.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, pages 916-930.