Whenever I discuss sleep, I like to use pets as an example. Picture a dog putting itself to sleep. Well, first, let’s be honest… it has to sniff around the room a while to find the perfect spot–that oh-so-perfect place where there’s just the right amount of sun. Then it’ll make 5 circles around that spot before finally flopping on its side. But not just flop anywhere on the rug–it has to be that spot on the rug where half of its body is getting direct sunlight and the other half is in the shade. Once this perfect spot has been found, sleep sets in quickly. Within just a few minutes, your dog will go from completely awake to being in a state of deep sleep, where its eyelids are fluttering and its legs are twitching as visions of chasing some varmint dances through its head.
It’s that deep, restorative sleep that our bodies need so badly. This is what helps us perform at our best when we wake up. Animals, like cats and dogs, can achieve this state of deep restorative sleep really quickly. That’s partly why they don’t need to sleep for 7 or 8 continuous hours at a time like we do. They can take a quick snooze or “cat-nap” and be back up on their feet and ready to go after just 10 or 15 minutes of rest.
The Stages of Sleep
As human beings we have 2 stages of sleep that our bodies fluctuate in and out of throughout the night. There’s the Rapid Eye Movement (REM) phase and the Non-Rapid Eye Movement (NREM) phase. To make things just a bit more complicated, the Non-Rapid Eye Movement phase actually has 4 stages, where stages 1-2 are what we would call “light sleep” and stages 3-4 would mean the person is in “deep sleep.”
When someone is in stages 1 and 2, the slightest sound might wake them up. But in stages 3-4, it may be harder to wake them up.
Stages 3-4 are most important for our health. (In case you’re wondering how scientists identified these stages, they had people come into a sleep lab where they hooked them up to these machines that read their brainwaves and body temperature while they slept.)
That’s just NREM sleep. REM sleep is also important for feeling your best. For most of us, it takes about 90 minutes to get to this phase of deep sleep. Remember how a quick nap is so restorative for our pets? Well, we’re built quite differently. We need a minimum of 7 hours to allow our bodies to go in and out of all the stages of NREM and REM sleep. When that happens, we wake up feeling refreshed.
How Alcohol Affects Sleep
Depending on the amount of alcohol consumed, alcohol can act as a “depressant.” No, this doesn’t mean that by drinking it you will feel “depressed.” It simply means that it tends to slow down the body and mind. Caffeine, on the other hand, is called a stimulant in that it would have the opposite effect–it speeds things up.
Many folks will claim that alcohol makes them feel sluggish or sleepy. Because of this effect, they may use alcohol to help put themselves to sleep. After all, that’s what “nightcaps” are for, right? Well, this is partly true. Alcohol can make you fall asleep faster. But some have a lower tolerance to this effect, where others may have a higher tolerance. You may have a lower tolerance to alcohol while others may not have quite the same response–maybe they can consume more alcohol and not fall asleep as quickly or feel as groggy the next day.
The Rebound Effect
Here’s the really interesting thing: regardless of whether you have a high tolerance or a low tolerance to alcohol, while you’re asleep, your body is still metabolizing that alcohol and clearing it from your system. At some point during the night, while you’re asleep, something called a “rebound effect” happens. This means that instead of acting as a depressant like it normally would, once the alcohol clears your system, your body starts to wake up. And if you’re an otherwise healthy person with a normal functioning liver, this can happen 4-5 hours after you fall asleep (depending on how much alcohol you consumed before you hit the hay).
Think about it–the body is starting to wake up right in the middle of your sleep cycle! This is when you’re supposed to be moving in and out of stage 2 of non-rapid eye movement and REM sleep!
Sure enough, this is what scientists have discovered. When alcohol is consumed before bedtime, the body spends less time in the REM phase of the sleep cycle. You end up feeling tired and groggy the next day as a result, even though you may have slept for the recommended 7-8 hours. Added to this is the effect that alcohol may have on hormones, like growth hormone. Alcohol may decrease the amount of growth hormone secreted during sleep–that will definitely influence any gains you were hoping to achieve from your workout earlier in the day.