Adult bed-wetting is fairly uncommon. While incontinence is a difficult reality for some, the adult brain is adept at waking itself up when the bladder needs emptying. It’s also good at “holding it” until your morning alarm.
So why do the physiological rules — and years of adolescent training — go out the window when alcohol is involved?
It seems obvious: If you drink too much of anything in the later part of the day, you’ll need to relieve yourself in the middle of the night. If that consumption involves alcohol — particularly a lot of alcohol — then there’s a level of impairment that might prevent you from making it to the restroom, much less waking up first.
But it’s not that cut and, er, wet.
As anyone who’s ever had a drink knows, alcohol reduces inhibition, sometimes eliminating it entirely. “Normally, the limbic system or other primitive parts of brain want to do something, but the frontal lobe [is good at inhibiting] the ‘impulse’,” says neurosurgeon J. Mariano Anto Bruno Mascarenhas who we contacted via icliniq. “Alcohol [hinders] this inhibition and increases impulsiveness.”
When it comes to relieving ourselves, much of the action hinges on something called a micturition reflex. According to Mascarenhas, that reflex involves our brain sending a pair of signals — one that tells our body to fill our bladder and another that tells it to contract the detrusor muscles (those that form the bladder wall) and relax the sphincter.
Now, because the body wants to evacuate waste as soon as possible, normal micturition reflex is to empty the bladder when it reaches capacity. Through potty training and years of years and years of practice, however, the adult human brain is conditioned to not send pee signals unless a person is in a bathroom and clothing has been removed.
Seeing as alcohol reduces frontal lobe functions, “the inhibitory signals are lost and, as soon as the bladder fills, the detrusor contracts,” says Dr. Mascarenhas. “The sphincter opens and the person passes urine.” Et voilà: a wet bed.
Try explaining that to your friends after a few too many drinks. (“What’s the big deal?! My micturition reflex is compromised. It’s science!”) Or, using it as your excuse when someone you're sharing the bed with wakes to a sudden warm sensation at 5 a.m.