Sad middle-aged woman resting on pillow 1500 x 769 px

“Me thought I heard a voice cry ‘Sleep no more!

Macbeth does murder sleep’—the innocent sleep,

… The death of each day’s life, sore labor’s bath,

Balm of hurt minds, great nature’s second course,

Chief nourisher in life’s feast”

—Macbeth, William Shakespeare, 1600 AD.

Four hundred years later, UC Berkeley scientists used brain imaging techniques to explain Lady Macbeth’s sleep-deprived brain descent into the darkness of insanity. They studied 26 young adults, half of whom were kept awake for 35 hours straight and the other half were allowed a normal night’s sleep in that same time period. Their brain was then studied using fMRI imaging. This technique shows the blood flow to different areas of the brain, and by extension, their state of activation.


What did they find?

The amygdala is the area of the brain that deals with unpleasant (or aversive) emotions, and puts the body on alert to protect itself. For instance, feelings of fear or rage are processed there. In the sleep-deprived subjects, this area “lit up”, showing a high activation state.

On the other hand, the prefrontal area is responsible for tamping down those feeling, of adding some rationality into the mix; in a word, the outcome of its intervention is what we call “judgment”. In the sleep-deprived subjects, the level of activation of the prefrontal cortex was significantly reduced.

Subjects who had gotten a full night of sleep showed normal brain activity.

This is not surprising to anybody who has experienced sleep deprivation, and that’s essentially all of us. Who hasn’t experienced the easy irritability, or, alternatively, the giddiness that comes after a sleepless night? Or the compulsive and nervous eating? Or the feeling that your “resistance is down” and that you are prone to a viral cold? These feelings are not “all in your head”. Sleep deprivation has been shown to affect emotional well-being, to alter metabolic control, and to adversely affect the part of the immune response (called innate immunity) that protects us from bacterial and viral infections.


There may be more to it

If the capacity to tamp down negative thinking is impaired, it opens up the possibility of a connection to psychiatric disorders like depression and anxiety. If you think of it, both of these disorders are a reflection of inappropriate or exaggerated negative response to a stressful event. Such events need not be dramatic, they could be quite trivial. A not-so-good grade at school, perceived slight from a friend, a critical remark by a coworker—all these can precipitate depression or anxiety. And the brain mechanism is identical to that of sleep deprivation: An imbalance between the negative messages flowing from the amygdala and the moderating and rationalizing effect of the prefrontal cortex.


America the sleepless

How much sleep do we need? It varies with age and overall health. Most adults require 7- 8 hours a night. Older people may need 5-6 hours. Teenagers may require an hour or so more. Now consider the following:

  • The National Sleep Foundation poll found that in 1998, 35% of adult Americans got at least 8 hours of sleep a night. In 2005, this figure dropped to 26%.
  • About 40% of Americans get less than 7 hours of sleep.
  • 75% reported having some sleep disorder one or two nights a week.

These are sobering statistics. I can’t help but wonder if our chronic sleep deprivation is not a contributing factor to our elevated level of societal rancor, increased violence, our deteriorating civility, and our increased rate of diagnosed psychiatric disorders such as chronic depression, anxiety, and sociopathic behavior.

Sleep has become synonymous with sloth in our “on the go” society. It would take more than academic studies to change this culture. We need nothing less than a paradigm shift in our outlook on life.

Dov Michaeli, MD, PhD
Dov Michaeli, MD, PhD loves to write about the brain and human behavior as well as translate complicated basic science concepts into entertainment for the rest of us. He was a professor at the University of California San Francisco before leaving to enter the world of biotech. He served as the Chief Medical Officer of biotech companies, including Aphton Corporation. He also founded and served as the CEO of Madah Medica, an early stage biotech company developing products to improve post-surgical pain control. He is now retired and enjoys working out, following the stock market, travelling the world, and, of course, writing for TDWI.


  1. Have there been any studies on the differences between continuous sleep vs. quantity of sleep. In other words, is getting 5.5 hours of sleep and then 1.5 hours of sleep at some point later the same as 7 hours of sleep?

  2. Last summer I had a period when I didn’t sleep like 2 weeks in total. A friend of mine said that the time you need to recuperate it’s double from the one you lose or something like this. So, yes.. our body needs sleep.

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