BEEP! BEEP! BEEP!
Time to wake up and make it to school by at least 7:50 a.m. this morning. You’re racing through your folders praying that you completed your homework on algebraic equations and the Roman Empire. You’re probably wondering when you’re ever going to use this stuff again. You’re barely staying awake in class hoping the bell will ring for the day to be over.
Why can’t you stay awake?
Our bodies have an interesting way of maintaining a constant sleep schedule. In 1729 Jean Jacques d’Ortous de Mairan observed a mimosa plant and noticed that it raised its leaves during the day and lowered them at night. Thus, leading to the investigation of an internal biological clock that will produce circadian rhythms (about a day). (Ulrich-Lai, 2017)
Just like plants, we have a biological clock that persists within cycle lengths of 24 hours if kept constant in the environment. This clock helps maintain your fluctuating body temperature throughout the day. It persists while you’re running the mile during gym class, and maintains your metabolism while you ate the mystery special during cafeteria hours. (Ulrich-Lai, 2017)
Most importantly, it regulates your sleeping patterns.
The sub-cortical structure in the brain that has been coined the “master clock” is called the suprachiasmatic nucleus (SCN) in the hypothalamus. It has different genes that operate at day or night to regulate your sleeping patterns with projections to other sub-cortical structures to promote wakefulness and sleep.
So why is sleep so necessary?
There are a few explanations:
The Theory of Restoration - We rest in order to recover after a long day of work
The Theory of Adaptation - Sleep aids us in keeping out of trouble due to environmental risks
There are three functional states of the brain: Awake, where your thoughts are logical and progressive, Non-REM sleep, where there are no dreams and an idle body, and REM sleep, which has been described as “an active brain in a paralyzed body”.
What if you can’t sleep?
Your biological clock may not be set to 24 hours. It does not mean that you have some fatal disease. Everyone is different! But there are a few circadian disorders that shorten your biological clock based on gene mutations, which may cause advanced sleep problems.
The sleep center of the brain called the ventral preoptic nucleus (VLPO) has connections to the SCN. The flip-flop model highlights the switch between the sleep and arousal state, which helps prevent a person from being partially sleep or partially awake. If there are lesions in this system, it can lead to sleeping or awakening at inappropriate times, which is called Narcolepsy.
Sleeping is so fundamental to the importance of our health! Let’s remember that we should remain well rested even with hectic schedules in order to maintain our circadian rhythms!
Squire et al, Fundamentals of Neuroscience, 3rd Edition. Elsevier press (2003)
Saper et al, Nature 437: 1257 (2005)
Sakurai, Nature Reviews Neuroscience 8: 171 (2007)
Takahashi et al, Nature Reviews Genetics 9: 764 (2008)