Whether it’s a glass of wine or a shot of brandy, many are familiar with the sleep inducing effects of an evening drink. Alcohol is so popular, in fact, that up to 20% of Americans use it as a sleep aid to help them get some shut eye. But new research into how exactly alcohol affects sleep has revealed that it’s probably not the best way to drift off.
Researchers have observed for some time that alcohol affects how we sleep. Those under the influence take less time to fall asleep, for example. The problem is, that effect is short-lived. While falling asleep is easy, staying asleep is much harder, and the sleep during the second half of a night of drinking is often disrupted. The case is more severe in alcoholics who often have terrible insomnia followed by daytime drowsiness. The authors behind this new study sought to understand why that was the case.
Exactly why we sleep is still unknown, although there are numerous benefits to getting sufficient sleep, from improved memory and recall to increased learning ability. Insufficient sleep also leads to numerous health problems from obesity, diabetes and heart disease to death, often from drowsiness behind the wheel of a car. In spite of that, scientists think they have a fairly good sense of how our body regulates when it feels sleepy.
Two systems are involved: the circadian system and the homeostatic system. The circadian system works to promote wakefulness. The stronger the circadian rhythm becomes the more awake you feel. As the circadian system strengthens and recedes over the course of the day, you go from alert and awake to tired and sleepy in a cycle. Opposing this force and pushing you toward bed is the homeostatic system. This system uses the buildup of several brain chemicals to progressively increase sleepiness over the course of the day. The more of these chemicals there are in your brain, the sleepier you feel. Once you go to bed, these chemicals slowly recede.
The brain uses these two systems in balance. The desire to be awake promoted by the circadian system is balanced by the homeostatic system. Eventually, the homeostatic system builds up enough chemicals to overpower the circadian system, pushing you into sleep. As these chemicals recede, the circadian system also wanes, allowing you to get optimal shut eye. In the morning, the chemicals are gone and your body decides to wake whenever your circadian rhythm kicks you out of bed to start the whole process over.
What these researchers found is that alcohol wreaks havoc on the homeostatic system that uses chemical buildup to make you drowsy. In studying the sleep of both alcoholic and binge-drinking mice, the researchers found that key signs of the homeostatic system changed with alcohol consumption while leaving the circadian system alone. Alcohol shifts the whole homeostatic system earlier so that now you feel sleepy before you would have otherwise.
The problem is, your circadian cycle is still the same and now overcomes your homeostatic system earlier than it would have before. While you might fall asleep earlier, you also wake up earlier as a result. With your homeostatic system now shifted, you feel too alert to fall back asleep. But brain chemicals now build up earlier in the day, making you feel drowsy before it’s time for bed. This sets up a vicious cycle of poor sleep and daytime sleepiness that worsens your sleep troubles rather than fixing them. The message from the research is clear: If you’re having trouble sleeping, don’t reach for the booze.