OTC treatment options

Treatments for short-term sleep problems are available over the counter. Although they cannot cure insomnia, they can help to promote better sleep.¹⁰

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Histamine is a central nervous system (CNS) neurotransmitter which acts in the brain via three receptors (H1, H2 and H3). It is a mediator of "wakefulness"¹⁵ which increases arousal in the circadian sleep/wake cycle.¹⁶ Therefore, it has an important function in maintaining wakefulness and alertness.¹⁵ Diphenhydramine, a sedating H1 antihistamine, crosses the blood-brain barrier to block the effect of histamine on the H1 histamine receptors, causing drowsiness.¹⁵

Diphenhydramine is effective in reducing sleep onset (i.e. time to fall asleep) and increasing the depth and quality of sleep.¹⁷