Sleeping Cat

- Antihistamines, such as diphenhydramine (Benadryl) and doxylamine (found in various OTC medicines, such as NyQuil)
- Alcohol – Often, people start drinking alcohol in order to get to sleep (alcohol is initially a sedative and will cause somnolence, encouraging sleep). However, being addicted to alcohol can lead to disrupted sleep, because alcohol has a rebound effect later in the night. As a result, there is strong evidence linking alcoholism and forms of insomnia. Alcohol also reduces REM sleep.
- Barbiturates cause drowsiness and have actions similar to alcohol in that they have a rebound effect and inhibit REM sleep, so they are not used as a long-term sleep aid.
- Melatonin is a naturally occurring hormone that regulates sleepiness. It is made in the brain, where tryptophan is converted into serotonin and then into melatonin, which is released at night by the pineal gland to induce and maintain sleep. Melatonin supplementation may be used as a sleep aid, both as a hypnotic and as a chronobiotic.