NICE CKS advises against recommending OTC treatments for insomnia, whether it is acute or chronic.3

NHS Health A to Z does include the use of antihistamines such as diphenhydramine in its online advice on managing short-term sleep problems, but with caveats. People looking for advice on treating insomnia are advised: “You can get sleeping aids from a pharmacy. But they will not get rid of your insomnia and they have many side effects. Sleeping aids can often make you drowsy the next day. You might find it hard to get things done. You should not drive the day after taking them.”1,22

The BAP guideline notes that the non-selective sedating antihistamines sold OTC as sleeping medications have limited evidence around efficacy. However, it cites research supporting diphenhydramine used for two weeks for mild insomnia, and promethazine, which has a more profound effect, but its longer half-life means carry-over effects are more likely.4

While herbal products intended for sleep aids are generally considered safe and well tolerated, a recent systematic review found “a scarcity of evidence on the efficacy of each product in clinical studies”.23

Valerian inhibits GABA reuptake but studies disagree on whether or not valerian improves sleep quality. Based on the available data, valerian may be more effective for chronic insomnia than acute episodes. Lavender oil may have anti-anxiety activity and a calming effect, and possibly improve sleep quality.