Earlier this week, SLM spoke with Dr. Mark J. Muehlbach, a sleep specialist and clinical director of the Clayton Sleep Institute, about 10 habits that might be disrupting your sleep. There are three items on that list, in particular, that can be habit-forming: caffeine, nicotine, and alcohol.
In the U.S., nearly 18 percent of adults, or approximately 42.1 million Americans, smoke cigarettes. We also consume more caffeine than any other nation in the world. And since both of those substances are stimulants, people who consume one or more might be more likely to drink alcohol for its sedative effects to help them unwind at day’s end. Widespread use of these sleep-altering substances is one reason that the Center for Disease Control calls sleep insufficiency a “public health problem,” with an estimated 50 to 70 million chronically sleep deprived adults in the U.S.
Muehlbach shed some light on six ways nicotine, caffeine, and alcohol can affect your sleep:
1. Caffeine tricks us into thinking we’re alert.
Our internal clock is pretty smart. Once the sun goes down, our bodies tend toward sleep by producing the sleep hormone melatonin. Experts identify a chemical called adenosine, which builds in the brain during wakefulness, as another substance related to “sleep drive.” As adenosine levels increase, the chemical starts to inhibit certain brain cells that promote alertness, making us sleepier. Caffeine's been shown to temporarily blocks adenosine receptors in the brain, making us feel more alert, even when we’re supposed to feel tired.
2. Stimulants disrupt the natural sleep cycle.
Many people claim that caffeine doesn’t disturb their sleep. “Even if you can fall asleep after a pot of coffee, it does affect the quality of your sleep,” says Muehlbach. Caffeine stays in the system hours after consumption, which keeps people in a lighter level of sleep. Research shows that caffeine reduces the quantity of “deep sleep” or slow-wave sleep and REM sleep, the dreaming stage associated with memory and learning. Consumed within six hours of bedtime, caffeine is known to reduce total sleep time by more than an hour. The problem, as one study reported, is that participants weren't aware of the disruptive effects that caffeine was having on their sleep. One reason people might not realize that caffeine is harming their sleep is because they’re chronically sleep deprived. “If they aren’t getting enough sleep on a routine basis, they drink caffeine all day long to stay awake and don’t get enough sleep at night," says Muehlbach. "It catches up with them, though.” Break the cycle by avoiding caffeine six hours before bed. Nicotine has a similar affect on sleep, but it's quicker to leave the system; experts advise refraining from smoking for at least two hours before bedtime.
3. Smoking increases the risk of developing sleep apnea.
Studies indicate a distinct connection between smoking and obstructive sleep apnea, the most common type of sleep apnea disorder. It's defined by intermittent episodes throughout the night in which the throat muscles collapse and obstruct breathing. One study found that current smokers are 2.5 times more likely to have obstructive sleep apnea than non-smokers. The main reason: Nicotine irritates tissue in the upper airway, causing inflammation that can further restrict airflow during sleep.
4. Withdrawal symptoms don’t wait for any alarm.
Although nicotine-withdrawal symptoms are typically more pronounced, caffeine withdrawal could also be waking you up. Both caffeine and nicotine destroy the restful quality of sleep by reducing time spent in the deeper stages of sleep. Nicotine withdrawal, however, can affect your sleep in ways caffeine does not. Researchers from the University of Florida found that “for every one cigarette you smoke, your total sleep time decreases by 1.2 minutes.” Scientists speculate that some of this is due to restlessness from withdrawal symptoms, which often happen early in the morning, waking smokers before their alarm does.
5. Alcohol reduces REM sleep.
Like other sleep experts, Muehlbach acknowledges the fact alcohol helps you fall asleep. He also acknowledges the trade-off: “Alcohol is a sedative, so it does help you fall asleep, but it tends to disrupt sleep during the second half of the night.” On the one hand, alcohol has been shown to increase the time we spend in deep or slow-wave sleep, while decreasing time spent in REM sleep—the stage in which dreaming, learning, and memory occurs. More deep sleep sounds good at first, but our natural sleep cycle is complex; it needs just the right balance of deep and light sleep. “As alcohol metabolizes in the body, it begins to make sleep more fragmented during the second half of the night,” Muehlbach explains. “Even if you fall asleep faster, these little disturbances that happen later mean you won’t be getting a good overall quality of sleep.” One or two drinks earlier in the night is considered the safe range.
6. Like nicotine, alcohol worsens sleep apnea symptoms.
People with obstructive sleep apnea need to be especially careful when consuming alcohol. Because it’s a muscle relaxant, alcohol can make the muscles in the throat relax more than normal. For someone struggling with sleep apnea, mixing booze and sleep can be dangerous, or even deadly. Take precautions, and avoid excessive alcohol consumption if you have a sleep apnea diagnosis or tend to snore during the night.
