Sleep: A Critical BodyWHealth Enabler

I consider sleep to be the third essential component of BodyWHealth. Exercise and diet remain the first two, given their known impact on our health. Inadequate sleep will jeopardize gains you make by exercising and eating healthy! Adequate sleep helps you fight against the downward physical and mental spiral associated with aging.

“Early to bed and early to rise makes a man (person) healthy, wealthy and wise”.

The quote comes from Poor Richard’s Almanac (circa 1735), Benjamin Franklin’s scientific journal. He had foreshadowed truths that modern science continues to unravel.

Why do we sleep? Two major theories receive popular support from experts. First, sleep allows the body to repair and rejuvenate (the Restorative Theory). Growth hormone release, muscle growth, tissue repair, and synthesis of key restorative proteins all occur predominately during sleep. Second, sleep enables structural and organizational development of the brain (the Brain Plasticity Theory). Babies and young children sleep for 13 to 14 hours per day to help their brains to develop. In contrast, sleep deprivation impairs learning and intellectual performance.

Do we sleep enough? No! In 1992, concerns about changing sleep habits prompted a study by The National Commission on Sleep Disorders. The report, titled “Wake Up America! A National Sleep Alert”, revealed that Americans were sleeping 20% less than a century earlier. More recently, this was estimated to cause almost 40,000 casualties per year. Modern social development has outstripped evolution. We’re living at a pace that our bodies have not yet adjusted to, with significant negative results.

What is healthy sleep? A “normal” night is characterized by 4 to 5 sleep cycles each lasting about 90 minutes. In each of these cycles, four stages of slow-wave sleep (slow waves of electrical activity in the brain) are followed by 1 period of Rapid Eye Movement (or REM) sleep. Physical and mental restoration occurs during slow wave sleep. The function of REM sleep remains largely a mystery. This is the phase of sleep in which we dream. It is characterized by intense brain activity, rapid eye movements (with closed eyes), elevated heart rate and breathing, and muscle paralysis that presumably protects us against physical injury that may occur if we acted out our dreams. Adults have up to 2 hours of REM sleep per night, while infants have much more (up to 50% of their sleep), suggesting that it may be associated with mental development. The opposite of sleep is alertness. With “normal” sleep patterns, we have two daytime alertness peaks; one during the morning and the other during the late afternoon. These are separated by an early afternoon dip.

The health benefits of sleep have been studied by watching the impact of sleep deprivation and observational studies that look for associations between sleep patterns and disease prevalence. Two critical concepts have emerged:

Sleep need is defined as the pressure to go to sleep. It builds from the moment we open our eyes in the morning. We can measure sleep need using levels of a chemical called adenosine in the brain. The effect of adenosine is temporarily hidden by caffeine, leaving the coffee drinker less aware of the need for sleep. Sleep need is “reset” by a full night’s sleep.

If you don’t get enough rest the sleep need is not reset, and you begin to accumulate sleep debt. A cumulative deficit grows with long-term sleep deprivation. Scientists believe that daytime drowsiness is a warning sign of excessive sleep debt. The good news is that we can work off this debt by restoring healthy sleep volume.

Cumulative sleep debt results in unwanted health consequences. In the short term, we see impaired judgment, reduced reaction times, and bad moods. Studies have demonstrated neurological and mental impairment after an all-nighter that is similar to having a blood alcohol level of 0.05% (that’s legally intoxicated). Over the long-term, sleep deprivation results in an increased risk of stress-related illness, major depression and alcohol abuse, heart disease, high blood pressure, obesity, diabetes and early death. Sleep debt has been demonstrated to increase appetite, resulting in additional intake of calories (an average 500 per day) without a corresponding increase in calorie burn. Sleep deprivation is also associated with disrupted immune function. In a dramatic animal model, sleep deprivation causes immune paralysis and rapid death. Overall, sleep debt appears to accelerate normal aging, with the premature appearance of disease usually associated with older individuals.

If you’re interested in reading further, you should research the legendary Professor William (Bill) C. Dement. Known as the “Father of Sleep Medicine”, he is Professor of Sleep and Dreams at the Stanford Center for Sleep Sciences and Medicine. Over his illustrious career he has driven our understanding of sleep science, and founded the first sleep disorder clinic. For many years he has offered one of the most popular courses offered to undergraduate students at Stanford.

What is the right amount of sleep? We don’t have a generalizable recommendation. Sleep need is highly individualized. The best way to answer this for yourself is by tracking your level of alertness through the day. After a lifetime of research Professor Dement offers us pragmatic advice. He suggests that we should “sleep until you can’t sleep any more”.

My take-home advice for BodyWHealth:

  1. Sleep enough to stay alert during the day. This will help you to retain your youth for longer. For most of us this means sleep more.
  2. Use your daytime alertness peaks wisely. They are your most productive times!

Have fun,

Roddy

If you’re interested you can read more about the association between sleep debt and energy metabolism (including obesity) here:

  1. Poor sleep erodes WHealth
  2. Sleep well to lose weight

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