What is sleep? Why do we sleep? How much sleep do we need? What is its impact on our health?
In this brief article, I’ll present some relevant science, both new and established, that reveals the importance sleep plays in our overall health and our ability to function optimally at work.
Sleep is an important part of your daily routine. We spend about one-third of our time doing it. Quality sleep depends on getting enough of it at the right times and is as essential to survival as food and water.
Without sleep, you can’t form or maintain the pathways in your brain that let you learn and create new memories, and it’s harder to concentrate and respond quickly.
Surprisingly
- Sleep is important to a number of brain functions, including how nerve cells (neurons) communicate with each other.
- Your brain and body stay remarkably active while you sleep.
- Recent findings suggest that sleep plays a housekeeping role that removes toxins in your brain that build up while you are awake.
- Sleep affects almost every type of tissue and system in the body, from the brain, heart, and lungs, to metabolism, immune function, mood, and disease resistance.
- Research shows that a chronic lack of sleep, or getting poor quality sleep, increases the risk of disorders including high blood pressure, cardiovascular disease, diabetes, depression, and obesity.
Sleep Mechanisms
Sleep is regulated by two internal biologic mechanisms which work together:
The circadian rhythm and homeostasis.
Circadian rhythms are physical, mental, and behavioral changes that follow a daily cycle. They respond primarily to light and darkness in an organism’s environment. Sleeping at night and being awake during the day is an example of a light-related circadian rhythm.
Sleep-wake homeostasis is the balance of two opposing systems, one that wakes you and the other that puts you to sleep. The longer you’re awake, the greater the drive for the sleep is amplified.
The 5 Stages of Sleep
We cycle through 5 stages of sleep 4-6 times each. The length of each stage shifts as we move through these cycles from falling asleep to waking. This is known as “sleep architecture.”
Each phase of sleep shift is related to our brain waves. Brain waves are measured by Hertz (Hz), the number of cycles per second. (Beta, Alpha, Delta, Theta, Gamma)
Stage 1 – This is the lightest stage of sleep, the transition phase, where you feel yourself drifting off. If you were to forget about the alarm clock and allow yourself to wake up naturally, Stage 1 sleep would be the last stage before you fully wake up. You don’t spend too much time in Stage 1 sleep, typically five to 10 minutes, just enough to allow your body to slow down and your muscles to relax.
Stage 2 – The second stage of sleep is still considered light sleep. Your brain activity starts to slow down, as well as your heart rate and breathing. Your body temperature falls a little, and you’re beginning to reach a state of total relaxation in preparation for the deeper sleep to come.
Stage 3 – This is the start of deep sleep, also known as slow wave sleep. During stage 3, your brain waves are slow “delta waves,” although there may still be short bursts of fast brain activity (also known as beta-waves). If you were to get awakened suddenly during this stage, you would be groggy and confused and find it difficult to focus at first.
Stage 4 – Of the five stages of sleep, this is the one when you experience your deepest sleep of the night. Your brain only shows delta-wave (slow wave) activity, and it’s difficult to wake someone up when they’re in Stage 4 of sleep. Stages 3 and 4 can last anywhere from 5 to 15 minutes each, but the first deep sleep of the night is more likely to be an hour or so. This is the time when the body does most of its repair work and regeneration.
Stage 5 – This is the stage of sleep when you dream. It is also referred to as “active sleep” or REM sleep, which stands for the rapid eye movements that characterize Stage 5. During REM sleep, your blood flow, breathing, and brain activity increases. An EEG would show that your brain is about as active as it is when you’re awake. Another aspect of Stage 5 sleep is that the muscles in your arms and legs will go through periods of paralysis. Scientists speculate that this may be nature’s way of protecting us from acting out our dreams.
In next month’s article I’ll share why we sleep, how much do we need, and the benefits and consequences of adequate vs. inadequate sleep.
Please contact me with questions or a complimentary consultation. Email me at DrRonEccles@gmail.com or call me at 484-515-4040.
