It’s not hard to guess why 20% of American adults use alcohol to help them fall asleep—after all, the reasoning behind it seems sound. Consuming even a little bit of alcohol leads to drowsiness in most people, so, for believers in the nightcap, a little drink before bed serves as a way to drift easily into sleep without any tossing or turning. The problem is that sleeping is so much more than being unconscious.

During natural sleep, your brain is very much like the conductor of a symphony orchestra. It draws you in with a soft and quiet prelude, and then it progresses through the movements (or stages) of sleep in a beautiful cycle, culminating in a finale where we wake refreshed and energized for the new day. Throughout this symphony of sleep, your brain is performing lots of intricate maintenance, either on the body (developing and repairing) or on itself (strengthening memories and making connections between your daytime experiences).

“Sleeping” with the help of alcohol, on the other hand, is really only a poor imitation. If natural sleep is an hours-long, detailed symphony, a tipsy sleep is more like listening to radio static—it’s an unpleasant experience, and there’s not much going on during it. Let’s take a closer look at the many reasons that a nightcap just can’t quite match up with sleep au natural:

Up all night

In his eye-opening book Why We Sleep, sleep scientist Matthew Walker tells us that the sleep we enter after drinking is more like anesthesia than real sleep, due to alcohol’s sedative effect. As Walker says, instead of helping you fall asleep, alcohol merely “sedates you out of wakefulness”.

Also, unlike natural sleepiness, the drowsiness of alcohol eventually wears off part way throughout the night, leaving you more prone to small wake-ups that steal away any good rest sleep has to offer. Walker adds that, since most will not remember these small wake-ups, they fail to associate the next-day tiredness they feel with the alcohol-caused wake-ups they experienced throughout the night. It’s thanks to this that evening drinking looks completely innocent in most people's eyes, despite most likely being the culprit behind their fatigue.A not-so-dreamy sleep

The most ruinous effect of alcohol is actually something much less obvious to the lay-sleeper. Walker tells us that, as a by-product of your body metabolizing alcohol, the chemical aldehyde is created, and aldehydes are known to block your brain from entering REM sleep (also known as dream sleep).

One of REM sleep’s primary roles is solidifying complex memory in your brain, helping you to make connections and identify patterns. This useful skill is thus impaired by the effects of alcohol on your sleep. And as far as waiting for the weekend goes: alcohol’s blocking of REM can dismantle learned information even when you enjoy evening drinks days after your brain has gathered and stored the information.

Ruined rhythm

Making this nightcap an ongoing habit will simply introduce more long-term problems. Studies have shown that alcohol throws your very helpful circadian rhythm off-balance, preventing your sleep and alertness pattern from syncing up with the natural flow of daylight. Our circadian rhythms also dictate a lot more than just our sleep-wake cycle, so continuing to throw it off also means heightening the risk of developing various health problems (along with wrecking the consistency of your sleep).

The best advice

If you are one of the many who use an occasional nightcap as a sleep aid, the best thing you can do for your sleep is to start scaling back. The not-so-fun but healthy ideal is to cut out any alcohol remotely close to bedtime. The truth is that it’s just not worth the risk to your sleep health, and your health overall.

If you find yourself constantly fighting to get to sleep naturally and you’re stuck looking to alcohol as your only help, you should consult your doctor as soon as possible. A long-term problem with falling asleep can often be a sign of an underlying condition.

No imitations

If you’re unwinding with a glass of wine every once in a while, chances are you’re aware of your need for sleep—that’s a good thing! Just remember: what the science behind alcohol’s effect on sleep shows us is that, when it comes to sleep, there’s nothing quite like the real thing.