Week 2: Understanding sleep

Welcome to the third post for this project. In the previous post, I explained my progress in a literature review I am currently conducting to learn about sleep and light pollution. I learned about how exposure to artificial light affects the quality of sleep in both humans and animals . This week, I have been reading The Science of Sleep: What It Is, How It Works, and Why It Matters. In this post, I will explain my analysis of what I have read so far and will also describe my future direction for the weeks to come. 

Chapter 1 of this book covers the following concepts: 1) What sleep is 2) How the electrical activity of the brain is measured 3) The organization of the sleep stages 4) How sleep studies are performed 4) REM sleep and Non-REM sleep 5) How much sleep we need vs how much we get 6) relevant information about neurotransmitters and 7) what dreams are. This first chapter provides us with a great introduction to information we should know about sleep. Relevant information covered in later chapters talk about the consequences of failing to sleep healthily, the circadian rhythm, circadian regulation models, the relationship between melatonin and sleep, how aging is related to sleep quality, the hormones secreted during sleep, and sleep disorders. In this post, I will be talking specifically about some of the most important information I learned from the first chapter. My next post will discuss relevant information from the chapters to follow. 

The book describes sleep to be a period of decreased awareness and the “rhythmic appearance” of certain stages. The stages can be defined by looking at an electroencephalogram which allows us to observe the brain waves, along with an electrooculogram which records eye movements, and an electromyogram which measures muscle activity. The period of sleep can be broken down into the following stages: the waking stage, the three non-rapid eye movement stages, and the rapid eye movement stage. The waking stage is when we are alert, and our brain waves are dominated by beta waves. The NREM sleep stages can be categorized by the following stages: N1, N2, and N3. The N1 stage is considered drowsiness. The brain waves slow down from beta waves to alpha waves, eye movements slow down, and muscle activity decreases. In N2, brain waves continue to become slower but there is also activity called sleep spindles, which are bursts of faster activity. In N3, brain waves become very slow and turn into delta waves. This stage is crucial for growth hormone release and physical healing. The REM stage is when we have bursts of rapid eye movements, but there is very little muscle activity. It is during this stage that we dream. Our brains are highly active, and our brain waves are similar to the waves in the waking stage. We consolidate memories and process emotions. As we sleep, we cycle through the stages of sleep multiple times, with the sleep cycle starting with the NREM stages and progressing to REM sleep. 

Although I will not be utilizing the devices necessary for analyzing the brain activity of my subjects as they sleep, I will be utilizing a questionnaire which will be used to qualitatively analyze their quality of sleep. The book mentions that although studies say that typical sleep is in the area of 7.5 to 8.5 hours, “primarily about 8.17 hours”, the amount of sleep we need is difficult to define. We learn about sleep debt, which is a term used to describe lack of sleep. The book describes that a sleep debt is difficult to compensate for, as there are physical limitations such as the natural body clock which would prevent one from simply sleeping for an appropriate length of time after attempting to sleep at the beginning of the morning, or something of the sort that is unnatural. One particular consequence of developing a sleep debt is that waste products of metabolism are not able to be as efficiently cleaned out from the brain. There are several other consequences of lack of sufficient sleep, and the factors which define sufficient sleep may slightly vary depending on an individual’s specific circumstances, environment, and health.

As I continue to learn about sleep via reading this book and other sources of information, I will continue to finalize both my initial survey and short questionnaire (that will be taken nearly daily) which will be sent out to the subjects soon. I will also be reading about artificial light and its general impacts on sleep and beyond. Thank you for reading this post, and I look forward to updating you with my progress in this project.