eli5: Why do drugs that make you drowsy make you drowsy



eli5: Why do drugs that make you drowsy make you drowsy

In: Chemistry

It’s different from drug to drug, but many do it because they slow down the nervous system.


I’m going to assume you’re asking about over the counter sleep aids. Most of these are antihistamines like Benadryl. Histamines have a variety of effects the body, but the relevant part is the regulation of the sleep wake cycle. Benadryl and similar medications block histamines completely which makes your body think they’re in “off” mode or sleep mode making you tired. This drowsiness is a side effect as these medications are effective at reducing inflammation caused by allergic reactions which is what they’re for.

There are other prescription sleep aids that work on different systems in the body, but to put it simply, they cause an increase in chemicals in the body that make you tired when there’s more of them.

Drugs that make you drowsy are drugs that can reach the brain and affect the central nervous system. The depress the neutrotransitters in the brain.

Benzodiazepenes, for instance, which are used to treat conditions like anxiety and insomnia, boost the effect of a brain chemical that makes it harder for brain cells to fire, causing a sedative effect. The antihistamine diphenhydramine (Benadryl) uses a different mechanism to directly depress the brain’s arousal system

Other drugs such as beta blockers use to control blood pressure can cause fatigue and tiredness by reducing heart rate.