That glass of red wine, a nightcap, or beer before bed can be a sure-fire ticket to falling asleep easily. But while they might ease you into a deep slumber initially, they can end up robbing you of a good night’s rest.
“The problem is, in a single night, as the alcohol is metabolized during the second half of the night, it creates more fragmented sleep,” says neurologist and sleep expert Jessica Vensel-Rundo, MD.
Even though alcohol is a sedative, its effects wear off during the night, she says. “There’s more disruption. Deep sleep decreases during the second half, and REM, or dreaming, sleep increases.”
What alcohol does while you sleep
When you are sleeping with alcohol in your system, it can cause:
Vivid dreams and nightmares: With alcohol in your system, you’re more likely to have intense, colorful dreams and nightmares. There’s also a chance you’ll act out your dreams in your sleep or even sleepwalk.
“There are parasomnias where you have more sleepwalking or nightmares – even sleep terrors,” Dr. Vensel-Rundo says. “Dream enactments can happen with alcohol, as well as with antidepressants.”
Breathing problems: Alcohol’s sedative effect extends to the rest of your body, as well.
“One of the concerns with alcohol, specifically, is that it tends to relax the muscles. It allows your airway to close more easily,” she says. “So, it increases the risk of sleep apnea or worsens it if you drink within the last couple of hours before bedtime.”
Opiates – narcotics used to treat pain – present even greater dangers. They can trigger central sleep apnea, a condition where your brain fails to signal your lungs to breathe.
How you’ll feel the next day
If you drink alcohol or take a drug before bedtime, you can expect to wake up with some degree of grogginess, Dr. Vensel-Rundo says.
“From the sleep perspective, alcohol and drugs will make you feel like you’re not refreshed,” she says. “You’re likely to experience insomnia, fragmented sleep, or simply waking up more frequently.”
Stimulant medications, such as those used to treat Attention-Deficit Hyperactivity Disorder in adults and children, can also disrupt sleep and lead to depression, decreased motivation, insomnia or trouble waking.
Existing research also shows alcohol can decrease your melatonin levels, the hormone that regulates your body’s internal clock, she says. If you become dependent on drugs or alcohol, you could get your days and nights mixed up.
“Individuals who abuse drugs and alcohol often spend all night using these substances. They sleep during the day and binge at night,” she says. “Then, there’s a big sleep-wake reversal, and that has to be dealt with as someone comes off the drugs and alcohol.”