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Why We Sleep

One thing I am really serious about is my sleep. Maybe it is because of the gruelling training involved in becoming a surgeon during which time many of us are sleep-deprived. Perhaps that 5-year stretch of less than 6 hours of sleep per night awakened me to the difference I feel after a long, uninterrupted and restful sleep. It might have been that, but I think it may have started when I was a child. My mother is as equally focused on a good night of sleep as I and she imparted this upon me at a young age. It is a known fact amongst my friends that I am neurotic about my sleep and this has led to me being the target of many a joke. Suffice it to say, I am always on the look out for ammunition that supports my position on sleep. As such I jumped at the chance to read a book entitled “Why We Sleep” recommended by one of my colleagues. Even as a self-proclaimed sleep enthusiast, this book has been a game changer for me. Despite 13 years of school and training I had no understanding of the scope of importance of an average of 8 hours of sleep per night.

One interesting historical fact is that the “Father of Surgery” William Stuart Halsted (also the name associated with the ‘Halsted Mastectomy’) was also the founder of the surgical residency. His position was that time spent sleeping was at the detriment of time spent learning. He practiced what he preached and spent hours on end dedicated to his job. However, Halsted was also addicted to cocaine after self-experimentation with the drug for use as an anesthetic; a fact that he kept hidden from his colleagues and trainees. Unfortunately the Halsted mandate to forgo sleep in the pursuit of surgical education has permeated through generations of surgical trainees and is now realized in the typical under-slept state of our surgical trainees and doctors. A few sobering facts: after a 30 hour shift a doctor will commit 36% more serious medical errors and 460% more diagnostic mistakes. One in twenty residents will kill a patient due to lack of sleep. Surgeons who have not been allowed at least a six-hour sleep opportunity the night before surgery have a 170% increased risk of inflicting a serious surgical error such as organ damage. In my day-do-day it is a common occurrence to speak to another surgeon over the scrub sink preparing for a full slate of surgical cases after having been up for 24 hours.

Matthew Walker is the author of ‘Why We Sleep’. I checked him out and he is well credentialed: Professor of Neuroscience at Berkeley, Director of the Sleep and Neuroimaging Lab at Berkeley, former Professor of Psychiatry at Harvard and author of a score of publications in reputable journals. So I think he is a legitimate source of information on the subject. I took away a few take-home messages and it also got me thinking about sleep and breast cancer. I decided to do a little digging into whether sleep might affect breast cancer risk and I have summarized my findings on sleep and breast cancer below as well as my take home messages from the book.

The first study that I found “Sleep Quality, Duration, and Breast Cancer Aggressiveness” was published in 2017 by Soucise et. al. out of the University of Buffalo. In over 4000 non Hispanic white females they found that those sleeping 6h/night on average were more likely to have breast cancers of worse stage at presentation than those that slept 7-8h/night. Another 2001 study from the Fred Hutchisnon Cancer Research Center in Seattle entitled “Night Shift Work, Late at Night and Breast Cancer” by Davis et al. showed a significantly higher incidence of breast cancer in women who work graveyard shift hours. One cause may be that decreased melatonin in these women (whose circadian rhythms were disrupted by the graveyard shift) blocked the protective effect of melatonin on estrogen receptors. Another cause may be the increased level of sympathetic nervous activity (like being in a highly inflammatory state) which occurs with lack of sleep. This can trigger a chronic inflammatory state which can influence the development and spread of cancer. Denmark has become the first country to offer compensation to graveyard shift workers who have developed breast cancer.

Here are some other interesting topics covered in the book:

1. Alzheimer’s disease – the poisonous compound associated with Alzheimer’s is not cleared by the brain unless we get a good (specifically NREM) sleep. Without sufficient sleep, amyloid plaques build up in the brain increasing the risk of Alzheimer’s. Take home : getting too little sleep across the adult life span raises your risk of developing Alzheimer’s disease.

2. Traffic accidents - Operating on less than five hours of sleep, your risk of a car crash increases threefold. Take home: do not drive when drowsy, drowsy driving accidents exceed those caused by alcohol and drugs combined.

3. Length of life – The shorter we sleep the shorter we live. This is a result of diseases such as heart disease, obesity, dementia, diabetes and cancer. Adults aged 45 years and older who sleep fewer than six hours a night are 200% more likely to have a heart attack or stroke during their lifetime. Physical fitness proves no match for a short night of sleep; it affords no resistance. Take home – all of the above diseases have recognized causal links to a lack of sleep.

4. Weight gain – individuals that sleep less than 6 hours per night will consume more than 70,000 extra calories than those sleeping 7-8 hours per night. This translates to 10-15lbs extra of weight gain per year. Take home – lack of sleep triggers your appetite leading to weight gain..

5. Cancer – Sleeping six hours or less is associated with a 40% increased risk of developing cancer relative to those sleeping seven hours a night or more. Take home – the World Health Organization has officially classified nighttime shift work as a “probable carcinogen”.

6. Our children need their sleep – earlier start times at school are depriving our children of much needed sleep which can result in decreased IQ, ADHD type symptoms, substance use and increased traffic accidents. Take home - as parents we need to impart the importance of sleep upon our children so that they may flourish and in turn improve the next generation.

What have I done as a result of reading this book? A few things:

1. I changed the temperature in my bedroom to 18.5C.

2. I use a sleep mask to black out my sleep.

3. An hour before bedtime I turn down the lights in my house.

4. I keep a strict and consistent bedtime and awakening time with an 8.5 hour sleep opportunity.

5. I try to limit my exposure to blue light prior to bedtime.

In conclusion: I would like to thank my mother for raising me to be a sleep enthusiast, I think it's going to pay off.

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