The Awake Brain
Your brain is designed to work in cycles. In the morning, your brain is in its it’s full functional state. Your sensory organs are fully engaged, allowing for sight, hearing, touch, taste and scent. Your eyes will operate normally, and your blink reflex (the response to a fast moving object coming towards your face) is active. You are also in complete control of your motor cortex, so you have full control of your muscles, allowing for normal movements.
Your heart beat is on an automatic system but gets outside input from the vagus nerve. Your heart rate will rise when physical demand requires more blood flow. Your breathing is automatic as well. You can override the automatic breathing cycle yourself by doing something like meditation or breath holding. Your respiratory system will go back to your default automatic program as soon as your conscious brain moves on to something else.
During the awake state, your digestive system is ready to work, and particularly during the day hours the stomach, small intestines, and colon work in coordination to digest for and extract nutrients as well as eliminate waste.
The Drowsy Brain
You begin to register the sensation of feeling sleepy when your blood pressure begins to drop. Your heart rate will also begin to slow down. Your ability to form new memories decreases, and any new information that reaches your brain will not be stored. The electrical activity in your brain begins to change as well which can be seen on an EEG. This corresponds to an alteration in your eyes, which will start an automatic slow back and forth movement.
N2 or light sleep will follow the first stage of sleep. The electrical activity of the brain will continue to change, reflecting a lower amplitude of activity on EEG’s. The eyes will stop moving at this point, tending to stay in one place. Breathing is now automatic. When your awake, if you hold your breath, you will get a strong urge to breathe within a few seconds due to your body’s mechanism to respond to elevated carbon monoxide levels in the blood stream. In N2 sleep, your body may not do this. You will spend about half of the night in this stage of sleep.
In this deeper stage of sleep, brain activity continues to slow even more. Your brain will cycle between N2 and N3 several times throughout the night. The body is even less responsive to rises in carbon dioxide in the blood stream than in the lighter stages of sleep.
REM, or Rapid Eye Movement, is the necessary sleep stage that allows for true rest. It is during this phase that the all motor control is frequently lost; This is the stage of sleep when dreams occur.
After going through several cycles of sleep throughout a night, your body will prepare to wakes itself. In the early morning hours, your blood sugar will rise. This effect can become exaggerated in diabetics, leading to the Dawn Phenomenon, or early morning high blood sugars despite being in a fasting state. The cycle starts again
Sleeping is a complex process, and as you can see, there are many steps in the process to ensure a good night’s sleep. I frequently discuss an abbreviated form of the the sleep process with patients because many people don’t realize that the highly coordinated process is deeply disrupted with alcohol, several medications, as well as bad habits such as ruminating at bed time.
Once again, I am so appreciative for readers that stop by to read my blog. Being a practicing physician, many of these important topics I often rush through, so it’s nice to spend a little more time on issues.
In my next insomnia post, I will start delving deeper into how to analyze your sleep issue and approaches to deal with them.
Goldman, L., & Schafer, A. I. (2016). Goldman-Cecil medicine. Retrieved June 2, 2018.