Welcome back fellow science nerds. I don’t know about you guys, but as the days get shorter and winter starts to poke its ugly head around the corner, I find myself feeling a lot sleepier throughout the day. My recent increase in sleepiness made me curious: why do we have to sleep? What happens to our bodies while we sleep? So I looked it up and now I’m going to share all that I have learned with you!
Long story short, scientists don’t know exactly why humans have to sleep, but we do know some of the reasons why we feel sleepy. One of the biggest reasons is our internal body clock. It operates on an approximately 24-hour sleep-wake cycle called a circadian rhythm. Some things, like traveling to a different time zone, can throw off this cycle. For example, when I traveled to Germany to study abroad I dealt with jet lag. There is a six-hour time difference between Germany and where I was living in the US. My body was very confused and it took me about a week or so to get back into a normal sleeping schedule.
There is also evidence suggesting a link between our sleep-wake cycle and an organic compound produced by the brain called adenosine. Throughout the day adenosine builds up in the brain, making you feel sleepy. As you sleep, your body breaks down this adenosine and flushes it from your system.
Light influences our sleep-wake cycle as well, which may be the answer to my question about why I seem to be so much sleepier this time of year. Part of our brain, called the hypothalamus, houses a group of cells called the suprachiasmatic nucleus. These cells process signals created when our eyes are exposed to light, both natural and artificial, which helps the brain determine if it is day or night. As natural light disappears, the body releases a hormone called melatonin. Melatonin increases the feeling of drowsiness in the body. As the sun begins to rise, the body releases a hormone called cortisol. Cortisol, also known as the “stress hormone”, promotes energy and alertness.
Now we know the different things that make us sleepy, what about what happens if we don’t get enough sleep? One of the most easily identifiable signs of not getting enough sleep is a decrease in cognitive ability. This can be the feeling of grogginess after a poor night of sleep. Your reaction time is delayed, you have difficulty focusing, and can experience mood swings. If sleep deprivation continues for long enough, humans can even experience hallucinations.
Chronic sleep deprivation can also cause long term negative health impacts. If you aren’t regularly getting enough sleep, you will be at higher risk of developing type 2 diabetes, obesity, high blood pressure, heart disease, mental health disorders, stroke, and even early death. People, and animals, that do not get adequate amounts of sleep have also been shown to have weaker immune systems, leaving them more vulnerable to various illnesses as well as the more chronic conditions mentioned before.
Now, you may be asking, what do our bodies do while we are asleep? For a long time, scientists believe that while we were sleeping it was almost like we were dead. Turns out, that is far from what is going on. While we sleep our bodies are hard at work repairing themselves. Muscle growth, tissue repair, protein synthesis, and growth hormone release have been shown to occur mostly, or even only in some instances, during sleep.
While our bodies are busy repairing themselves, our brain is also hard at work. Studies have shown that the brain is better able to remove waste cells while we are asleep. The brain is also sorting through and storing all of the information gathered throughout the day. This process is extremely important when it comes to creating long-term memories.
So listen to your body! Take care of yourself and get enough sleep! I have always been the type of person that requires a lot of sleep. I do not function well without getting enough sleep, so it is very important to me. Especially during these crazy, global pandemic, super weird, and stressful times, getting adequate sleep is essential. So make a good bedtime routine, take care of yourself, and stay healthy. Thank you for coming on this little journey and learning all about sleep with me. What surprised you the most about sleep? I was definitely surprised to find out that you can hallucinate if you don’t get enough sleep. Makes me want to go take a nap right now, just to be safe.
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