Why does Benadryl make you sleepy?
In: Biology
A fun quirk of physiology; it prevents the allergic/inflammatory receptors from activating by blocking the real activators from binding those receptors. It’s shaped wrong enough to block the response, but is shaped close enough to correctly, to trick your brain to think that you’re sick and need to sleep. Sleep is an active process, which Benadryl can kick off, while blocking the other nasty histamine driven processes. Serendipity really.
Benadryl is an anti-histamine drug. What is a histamine? A chemical produced by your immune system to fight off allergens (dust, pollen, etc.). Scientists have discovered a link between histamines and the sleep/wake cycle. The basic thought process is that when you are surrounded by an allergen you need to be put into a heightened state of awareness. But at the same time, your brain completely shuts off histamine activity during deep sleep.
By blocking histamines from being able to trigger an allergic response, you are basically starting a cascade of chemical reactions that lead to a sleepy state instead of an awake state.
Also know that some people are excited by Benadryl, supposedly because they metabolize the drug incredibly quickly such that they don’t activate the sleep/wake cycle effects.
Histamines and wakefulness:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3016451/
Antihistimine ultra-metabolizers:
https://www.ncbi.nlm.nih.gov/pubmed/18227744
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