Understanding Sleep in Lifestyle Medicine

Updated: Jun 9

Overview

Ever since I re-launched this website, I started discussing Lifestyle Medicine as a medical discipline and started the six areas of focus with nutrition. Each area of focus is important in itself and these should go along with the others. So enumerating them does not mean that is the order or a pattern to be followed. The next area of focus of Lifestyle Medicine I am going to share today is about sleep.


Isn’t it funny that although everyone sleeps, it is difficult for us to define precisely what sleep is? Try asking people randomly what sleep means to them and you will get different answers. Yet, and this is a reality, sleep is a human activity that almost everyone takes for granted.


Sleep Health and World Sleep Day

Last month, World Sleep Day® was celebrated. Yes, there is such a thing. It is held every Friday before Spring Vernal Equinox each year. For this year, it was held last March 19th. This annual event is intended to be a celebration of sleep and at the same time, create a call to action on important issues related to sleep which includes medicine, education, productivity, driving, and other social aspects of human life.


It goes to show that Sleep Health is being recognized as a component of Lifestyle Medicine. Sleep Health or sleep medicine is relatively new in the field of Lifestyle Medicine that scientific studies and related literature on sleep health are limited. Be that as it may, this article is going to provide you an overview of the key issues associated with sleeping habits and how to incorporate this knowledge into your own lifestyle for better health.


Definition of Sleep

Sleep is a body and mind activity which is natural, recurring, and reversible. It is characterized by altered consciousness, decreased responsiveness to external stimuli, inhibited senses, reduced muscular activity, reduced interactions with surroundings, rapid eye movement, and dreams. It is associated with a typical posture of lying down with eyes closed. Scientists say that during sleep there are brain wave activity changes, as well as changes in the rate of breathing, heart rate, body temperature and other physiological functions. Also, sleep is relatively easy to reverse which distinguishes it apart from coma and other disorders of consciousness.



The Anatomy and Physiology of Sleep

For many centuries, physicians used to believe that sleep was a period of physical and mental inactivity only to realize over the last 60 years that the brain remains active during sleep. In fact, several brain structures are involved in sleep.


The brain’s hypothalamus contains nerve cells that control sleep and waking up. Within the hypothalamus is the suprachiasmatic nucleus (SCN) that receives information about light exposure directly from the eyes and controls your behavioral rhythm. The brain stem (includes the pons, medulla, and midbrain) communicates with the hypothalamus to control the transitions between wake and sleep. A brain chemical called GABA is produced in the hypothalamus and the brain stem. It reduces the activity of arousal centers. The pons and medulla send signals to the limbs and other body muscles to relax so that you don’t involuntarily act out your dreams while sleeping. The thalamus which relays information from the senses to the cerebral cortex becomes quiet, letting you tune out the external world. During REM sleep, the thalamus sends the cerebral cortex images, sounds, and other sensations which make your dreams come alive. The amygdala becomes active during REM sleep because it processes the emotions. The pineal gland receives signals from the suprachiasmatic nucleus (SCN) which increases the production of melatonin, a hormone that puts you to sleep once it gets dark. The basal forebrain promotes sleep and wakefulness, while a part of the midbrain acts as an arousal system. Release of adenosine, a chemical by-product of cellular energy consumption supports your sleep drive.


There are two basic types of sleep: the non-REM sleep and the rapid eye movement (REM) sleep.


The first stage of sleep is a non-REM sleep that changes over from your wakefulness then it slows down to your sleep. This lasts for only several minutes, thus it is short. It is characterized by a relatively light sleep. Your heartbeat, breathing, and eye movements are slow. Your sk