Over-the-counter sleep aids are some of the most common medications found at pharmacies and grocery stores. They are regulated by active pharmaceutical ingredients and differ from natural and herbal sleep aids. The most common ingredients found in over-the-counter sleep aids are diphenhydramine and doxylamine. These two drugs are effective as sleep aids because they are antihistamines. First-generation antihistamines cause significant sedation and drowsiness, which is the desired effect when taken as a sleep aid. Over-the-counter sleep aids are generally safe but can cause side effects in some users.
Motor Impairment
Over-the-counter sleep aids commonly cause motor impairment through anti-cholinergic activity. This can occur before falling asleep, during the night if woken up and sometimes in morning even after a full night's sleep. Over-the-counter sleep aids are effective by relaxing the body in preparation for sleep, but this can turn into disturbed motor movement before and after sleep as well. According to Drugs.com, impaired motor functions and dystonic reactions are some of the most common side effects for Nytol, Unisom, Benadryl and Sominex, four of the most common over-the-counter sleep aids.
Gastrointestinal Impairment
People taking over-the-counter sleep aids also commonly experience dry mouth and throat and digestion problems as a side effect. This is caused by the anti-muscarinic effects of either diphenhydramine or doxylamine, the active ingredients found in sleep aids. According to the National Institutes of Health, diphenhydramine can cause dry mouth, nose and throat; vomiting; nausea; constipation; and loss of appetite. Because of the dry mouth caused by the medication, a decrease in healthy bacteria can also lead to dental carries. Users may also experience increased urinary retention from taking over-the-counter sleep aids.
Impaired Cognition and Memory
Memory and cognition problems often accompany over-the-counter sleep aids. These drugs act to block histamine, an essential component for maintaining alertness. After users wake up, it may take an hour or two to fully wake up, due to the residual effect of the drugs. In the June 2009 issue of "U.S. Pharmacist," Professor Darrel Hillisz and Pharm.D candidate Christine Duff stated that one of the most common side effects from over-the-counter sleep aids is the hangover effect the following morning. In addition, they state that because of their prolonged sedating and anti-cholinergic effects, they should not be used in elderly patients. In the August 2008 issue of "Neurology Now," Dr. Jack Tsao and Dr. Kenneth Heilman found that anti-cholinergic drugs, such as Benadryl or Unisom, can impair memory and cognition significantly. In the study, memory and cognition scores fell by 1.5 times compared to people who had not taken these medications.
References
- Drugs: Nytol Side Effects
- "Journal of Biomedical Sciences"; Antimuscarinic Actions of Antihistamines on the Heart; Huiling Liu et al.; February 2006
- National Institutes of Health: Diphenhydramine
- "U.S. Pharmacist"; Assisting Seniors With Insomnia: A Comprehensive Approach; Darrell Hullisz and Christine Duff; June 2009
- "Neurology Now"; Common Drugs May Cause Cognitive Problems; Jamie Talin; August 2008
