Sleep: Nature’s Gift of Health
Benjamin Franklin gave the gift of extra daylight hours to Europe, North America, and other countries around the world in 1784. Franklin couldn’t have known that in today’s time, this rite of spring wreaks havoc on drivers everywhere. In fact, there’s a documented 7% increase in motor vehicle accidents right after the change to daylight savings time. Brian Orrbine, senior policy advisor in road safety for Transport Canada admits, “Sleepiness is one of the major causes of accidents, after alcohol.”
Sleep takes up a major portion of our life, yet few people realize its impact on our health and wellness. Steeped in lifestyles filled with long job hours, shift work, stressful home lives and too much caffeine, we fail to realize that sleep is a precious commodity. Instead, we choose to give some of it up, expecting to put more things into our already stress-filled days.
In studies from both Canada and the U.S., more than half of all adults report going about their lives in a sleep-deprived state. In the U.S., one in five drivers reports falling asleep at the wheel. Worse yet, disasters such as the Exxon Valdez oil spill, Three Mile Island, the Challenger disaster and Chernobyl are believed to have their roots in sleep-deprivation. All of these facts highlight the importance of sleep as a health issue.
What is Sleep?
Sleep is a normal physiological state in which one has almost no awareness of one’s surroundings and engages in little physical movement. Individuals function poorly without sleep—with less than optimal coordination and mental processing. Key body functions, including those of the immune system, are also disrupted with a lack of sleep. Lack of sleep increases stress hormone (cortisol) levels and blood pressure.
Sleep is made up of two states: (1) Non-rapid eye movement (NREM) sleep and (2) Rapid eye movement (REM) sleep.
NREM sleep is divided into four stages, labeled 1 through 4, that are defined by the depth of sleep and the shape and depth of the brain waves noted on an electroencephalogram (EEG). Stages 3 and 4 of NREM sleep are called “delta sleep” due to the long, slow delta brain waves found on the EEG. This is the deepest type of sleep. Stages 1 and 2 are considered “light sleep” and make up the largest portion of our sleep. REM sleep is the part of sleep in which we dream. We need a balance of all types of sleep stages for the most restful sleep pattern.
Sleep evolves in infancy from many short blocks of sleep to a pattern of a single consistent block of sleep in adulthood. The average recommended amount of sleep for adults is 7-8 hours, however the optimal amount of sleep varies widely among individuals and ranges from 5 to 10 hours. Like many human physiological functions, sleep follows a circadian pattern, meaning that, in any twenty-four hour day, the natural urge to sleep and the natural urge to awaken follow a set daily pattern.
Understanding Circadian Rhythms
There is a huge interplay between the circadian pattern of sleep and the circadian pattern of many physiological variables, such as the normal daily variations in body cortisol levels, the levels of inflammatory proteins and the body’s melatonin level. In normal humans, there is a natural rise in blood melatonin in the evening which helps induce sleep. This elevated level coincides with the lowest levels of blood cortisol.
Cortisol is the body’s “stress” hormone. When we are under stress, cortisol increases. With high melatonin levels and low cortisol levels, it becomes easy to sleep. The opposite pattern is seen in the morning. Each morning, when melatonin levels are low and cortisol levels are high, it becomes relatively easy to wake up refreshed.
So what happens if we disrupt this normal pattern by becoming a night-shift worker, by leading an overly stressful life or by caring for an infant or a sick loved one during the night? Disrupting the body’s circadian patterns of sleep leads to secondary disruptions in all other patterns. For example, stress increases cortisol so the normal rise and fall that occurs during a 24-hour period is blunted. Melatonin patterns are also disrupted. The various cells and molecules involved in immunity also follow a circadian pattern and these, too, are found in abnormal amounts if sleep is lost or irregular. One particular immune mediator, known as interleukin-6 (IL-6), increases and loses its circadian pattern with lack of sleep. IL-6 is not considered a healthy immune mediator and is associated with excessive inflammation.
Health Effects Associated with Poor Sleep
Disrupting or shortening normal sleep patterns is more dangerous than one would think. Sleep-deprivation affects much more than your ability to drive or to think optimally. The elevation of interleukin in sleep-deprivation causes excessive body inflammation and may play a role in autoimmune disorders. The levels of natural killer cells drop, putting you at risk for infectious diseases.
Disturbing melatonin patterns results in an increased cancer risk in shift workers, airline pilots and nighttime truckers. A marker of excessive blood clotting, “fibrin D-dimer”, is increased in those who get disrupted sleep. This raises one’s risk for heart disease or stroke.
What Can Be Done to Stay “Sleep Healthy”?
While we can’t consciously control the body’s levels of the various hormones and infection-fighting cells, we can practice good sleep hygiene. When we do this, all of the other circadian patterns will fall into place, reducing our risk of sleep-related illnesses. The following sleep habits will maximize your chances of having a healthy sleep state:
- Don't exercise late in the evening.
- Don't smoke or use caffeine later in the day.
- Avoid napping during the day.
- Avoid alcohol during the evening.
- Have a regular pre-sleep ritual.
- Avoid food or fluids in the evening.
- Use your bed for sleep or sexual activity only.
- Don’t fall asleep with the TV or radio on.
- Don’t “sleep extra” on the weekends.
- Avoid exposure to very early morning light.
- Wear earplugs if your partner snores.
- Don’t lie in bed or watch the clock when you can’t sleep. Get up for a few
minutes, use the restroom and try to sleep again.
- Don’t linger in bed once you awaken in the morning.
- Keep a set sleep schedule.
- Reduce stress. Stress elevates the body’s cortisol levels which impair the ability
to sleep.
What You Can do If You Must Decrease Sleep Hours
Studies have been done to determine the optimal time to sleep, if you absolutely must cut back on sleep. As it turns out, staying up late and getting only four hours of sleep per night is better for your brain function than if you sleep early in the evening and get up early after four hours of sleep. Interestingly, either type of sleep deprivation is associated with a lower blood leptin level. Lower leptin means you eat more during the day. It’s likely that chronically sleep-deprived individuals are prone to overeating.
Our sleep, in many ways, is our lifeline to optimal health. Good sleep optimizes our immune system, our cognitive functioning and our physical abilities. It also likely reduces our risk for cancer, blood clots and infectious diseases. So treat yourself to sweet dreams.
Sleep takes up a major portion of our life, yet few people realize its impact on our health and wellness. Steeped in lifestyles filled with long job hours, shift work, stressful home lives and too much caffeine, we fail to realize that sleep is a precious commodity. Instead, we choose to give some of it up, expecting to put more things into our already stress-filled days.
In studies from both Canada and the U.S., more than half of all adults report going about their lives in a sleep-deprived state. In the U.S., one in five drivers reports falling asleep at the wheel. Worse yet, disasters such as the Exxon Valdez oil spill, Three Mile Island, the Challenger disaster and Chernobyl are believed to have their roots in sleep-deprivation. All of these facts highlight the importance of sleep as a health issue.
What is Sleep?
Sleep is a normal physiological state in which one has almost no awareness of one’s surroundings and engages in little physical movement. Individuals function poorly without sleep—with less than optimal coordination and mental processing. Key body functions, including those of the immune system, are also disrupted with a lack of sleep. Lack of sleep increases stress hormone (cortisol) levels and blood pressure.
Sleep is made up of two states: (1) Non-rapid eye movement (NREM) sleep and (2) Rapid eye movement (REM) sleep.
NREM sleep is divided into four stages, labeled 1 through 4, that are defined by the depth of sleep and the shape and depth of the brain waves noted on an electroencephalogram (EEG). Stages 3 and 4 of NREM sleep are called “delta sleep” due to the long, slow delta brain waves found on the EEG. This is the deepest type of sleep. Stages 1 and 2 are considered “light sleep” and make up the largest portion of our sleep. REM sleep is the part of sleep in which we dream. We need a balance of all types of sleep stages for the most restful sleep pattern.
Sleep evolves in infancy from many short blocks of sleep to a pattern of a single consistent block of sleep in adulthood. The average recommended amount of sleep for adults is 7-8 hours, however the optimal amount of sleep varies widely among individuals and ranges from 5 to 10 hours. Like many human physiological functions, sleep follows a circadian pattern, meaning that, in any twenty-four hour day, the natural urge to sleep and the natural urge to awaken follow a set daily pattern.
Understanding Circadian Rhythms
There is a huge interplay between the circadian pattern of sleep and the circadian pattern of many physiological variables, such as the normal daily variations in body cortisol levels, the levels of inflammatory proteins and the body’s melatonin level. In normal humans, there is a natural rise in blood melatonin in the evening which helps induce sleep. This elevated level coincides with the lowest levels of blood cortisol.
Cortisol is the body’s “stress” hormone. When we are under stress, cortisol increases. With high melatonin levels and low cortisol levels, it becomes easy to sleep. The opposite pattern is seen in the morning. Each morning, when melatonin levels are low and cortisol levels are high, it becomes relatively easy to wake up refreshed.
So what happens if we disrupt this normal pattern by becoming a night-shift worker, by leading an overly stressful life or by caring for an infant or a sick loved one during the night? Disrupting the body’s circadian patterns of sleep leads to secondary disruptions in all other patterns. For example, stress increases cortisol so the normal rise and fall that occurs during a 24-hour period is blunted. Melatonin patterns are also disrupted. The various cells and molecules involved in immunity also follow a circadian pattern and these, too, are found in abnormal amounts if sleep is lost or irregular. One particular immune mediator, known as interleukin-6 (IL-6), increases and loses its circadian pattern with lack of sleep. IL-6 is not considered a healthy immune mediator and is associated with excessive inflammation.
Health Effects Associated with Poor Sleep
Disrupting or shortening normal sleep patterns is more dangerous than one would think. Sleep-deprivation affects much more than your ability to drive or to think optimally. The elevation of interleukin in sleep-deprivation causes excessive body inflammation and may play a role in autoimmune disorders. The levels of natural killer cells drop, putting you at risk for infectious diseases.
Disturbing melatonin patterns results in an increased cancer risk in shift workers, airline pilots and nighttime truckers. A marker of excessive blood clotting, “fibrin D-dimer”, is increased in those who get disrupted sleep. This raises one’s risk for heart disease or stroke.
What Can Be Done to Stay “Sleep Healthy”?
While we can’t consciously control the body’s levels of the various hormones and infection-fighting cells, we can practice good sleep hygiene. When we do this, all of the other circadian patterns will fall into place, reducing our risk of sleep-related illnesses. The following sleep habits will maximize your chances of having a healthy sleep state:
- Don't exercise late in the evening.
- Don't smoke or use caffeine later in the day.
- Avoid napping during the day.
- Avoid alcohol during the evening.
- Have a regular pre-sleep ritual.
- Avoid food or fluids in the evening.
- Use your bed for sleep or sexual activity only.
- Don’t fall asleep with the TV or radio on.
- Don’t “sleep extra” on the weekends.
- Avoid exposure to very early morning light.
- Wear earplugs if your partner snores.
- Don’t lie in bed or watch the clock when you can’t sleep. Get up for a few
minutes, use the restroom and try to sleep again.
- Don’t linger in bed once you awaken in the morning.
- Keep a set sleep schedule.
- Reduce stress. Stress elevates the body’s cortisol levels which impair the ability
to sleep.
What You Can do If You Must Decrease Sleep Hours
Studies have been done to determine the optimal time to sleep, if you absolutely must cut back on sleep. As it turns out, staying up late and getting only four hours of sleep per night is better for your brain function than if you sleep early in the evening and get up early after four hours of sleep. Interestingly, either type of sleep deprivation is associated with a lower blood leptin level. Lower leptin means you eat more during the day. It’s likely that chronically sleep-deprived individuals are prone to overeating.
Our sleep, in many ways, is our lifeline to optimal health. Good sleep optimizes our immune system, our cognitive functioning and our physical abilities. It also likely reduces our risk for cancer, blood clots and infectious diseases. So treat yourself to sweet dreams.
posted by Kathleen Bell Kelley, MD @ 11:15 AM
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