It’s natural for many people to have a drink or two after work to wind down, or on the weekends as part of a social gathering. Many people even think a drink before bedtime helps them relax and fall asleep more easily. But contrary to popular belief, a nightcap can actually disturb your deep sleep and make you feel drowsy the following day. Drinking alcohol too close to bedtime can diminish the quality of your sleep, cause you to wake more during the night, and reduce the amount to time you spend in the restorative stages of sleep.

Initially, a drink of alcohol acts as a stimulant because it floods your brain with endorphins, the feel-good” hormone that your body makes. That’s why people become chattier, more confident, and lose their inhibitions when they drink. Later, when the buzz wears off, the sedative effects of alcohol kick in. That’s why people have mistakenly believed for years that alcohol is a sedative.

But a 2013 review of more than two dozen studies found that while drinking alcohol can ultimately shorten the amount time it takes to fall asleep, and it can increase deep sleep early in the night, later on it actually disrupts rapid eye movement (REM) sleep, that deep sleep your body needs to regenerate.

Most of the studies in the 2013 review found that Stages 3 and 4 of sleep were most impacted by alcohol. These are the stages when the body’s tissues repair and regenerate, bone and muscle are built, and the immune system is strengthened. When alcohol impacts these stages, you will not feel refreshed in the morning and the alcohol may create some obstructive sleep apnea.

Another study even found that the timing of a drink affected a person’s ability to sleep because of the impact on the body’s circadian rhythms. Circadian rhythms are the mental, physical, and behavioral changes that the body goes through over the course of a 24-hour cycle in response to light and darkness. Circadian rhythms work somewhat in tandem with the body’s biological or internal clock. While the internal clock controls the production of melatonin, the sleep hormone” produced by humans and all mammals, light determines when that hormone is produced—light inhibits melatonin production. Drinking in the evening and close bedtime caused the body to be stimulated more so than other times of the day.

Alcohol can also exacerbate problems in people with gluten sensitivity or who are already dealing with inflammation. Since beer is made from grains containing gluten, and wines and some liquors are made with sugar, a drink or two can make matters worse for some people. Food sensitivities can cause gut inflammation, which can affect the neurotransmitters (chemical messengers) in the brain. Since the neurotransmitters serotonin, dopamine, and GABA are actually created or built in the gut, if the gut is not working properly, then the brain is going to be impacted. That results in sleep disturbances.

Food sensitivities can also activate your immune system as a way of defending against an invader, causing inflammation that leads to brain fog, gas and bloating, constipation, low energy, or skin issues.

With all the downsides of drinking, for many people, it really makes more sense to skip the nightcap and get a good night’s sleep.