Sleep Deprivation Effects | Part 3

This part of Matthew Walker’s book on sleep is perhaps the most enthralling and simultaneously terrifying.  Sleep deprivation, more than anything else has been linked to heart disease, diabetes, cancer, gene transcription error and more.

My sister doesn’t live on normal-people time, both with night shift work once or twice a month, as well as very irregular sleeping hours.  And this line from the book in particular had me really hoping she would read this book and consider her sleep habits:

“The scientific evidence linking sleep disruption and cancer is now so damning that the World Health Organization has officially classified nighttime shift work as a “probable carcinogen”. (p166)”

Sleep Deprivation And The Brain

  • Research by David Dinges (University of Pennsylvania found in research that those who obtained six hours of sleep a night for ten days became as impaired in performance as going without sleep for twenty-four hours straight (p136)
  • With chronic sleep restriction over months or years, an individual will actually acclimate to their impaired performance, lower alertness and reduced energy levels and won’t be able to recognise their sub optimal existence. (p137)
  • Researchers in Australia found that after being awake for 19 hours, people who were sleep deprived wee as cognitively impaired as those who were legally drunk. (p138)
  • Infact each hour of sleep loss increases the likelihood of a crash.  E.g. At 6-7 hours you’re 1.3 times more likely to have a crash, and at less than 4 hours, you’re 11.5 times more likely to have a crash. After around 16 hours of being awake, the human brain begins to fail. (p139)
  • Sleep loss PLUS alcohol is not additive, it is multiplicable.
  • Vehicle accidents caused by drowsy driving exceeds those caused by alcohol and drugs combined.  Drowsy driving alone is worse than driving drunk.  When you’re drunk you will be LATE in reacting.  When you’re asleep, you stop reacting altogether. (p140)
  • Truck drivers are 200 to 500 percent more likely to be involved in a traffic accident.  And when a truck driver loses his or her life in a drowsy-driving crash, they will, on average, take 4.5 other lives with them. (p141)
  • The most dangerous time of flight in long haul travel is landing, which arrives at the end of a journey, when the greatest amount of sleep deprivation has often accrued. (p143)
  • A rare collection of individuals are able to survive on si hours of sleep and show minimal impairment.  The explanation appears to lie in the sub variant of a gene called BHLHE41 (also known as DEC2).  Expressed as a percentage of the population, the number of people who are like this are zero!  So it is very rare indeed. (p145)
  • Analysis of brain scans revealed the largest effects Matthew Walker has measured in his research to date – on the amygdala – which showed a 60% amplification in emotional reactivity in participants who were sleep-deprived. (p146)
  • Insufficient sleep doesn’t push the brain into a negative mood state and hold it there, instead it swings excessively to both positive and negative extremes. (p148)
  • Studies of adolescents have identified a link between sleep disruption and suicidal thoughts, suicide attempts and suicide completions in the days after. (p148)
  • Insufficient sleep also determines relapse rates in numerous addition disorders, associated with psychoactive substances. (p149)
  • Dr Allison Harvey from the University of California, Berkeley has found that should you improve sleep quality in patients suffering from several psychiatric conditions using cognitive behavioural therapy for insomnia (CBT-I), you can improve symptom severity and remission rates. (p151)
  • In one of Matthew Walker’s own experiments to understand the impact of students pulling “all nighters” – when comparing the effectiveness of learning between the two groups, there was a 40 percent deficit in the ability of the sleep deprived group to cram new facts into the brain relative to the group that obtained a full night of sleep.  That is the difference between acing an exam and failing it miserably. (p154)
  • In another test on 133 undergrads to learn a visual memory task, it was found that a night of sleep strengthened the newly learned memories, boosting their retention.  Additionally, the more nights of sleep participants had before they were ested, the better their memory was. Those who didn’t sleep the first night after learning, had no memory consolidation – i.e. if you don’t sleep the night that you learn, you lose the memories. (p156)
  • Dr Maiken Nedergaard at the University of Rochester found that a kind of sewage network called the glymphatic system exists within the brain.  This system collects and removes contaminants that are generated by the hard work performed by neurons in your brain.  It is at night, during deep NREM sleep that there is a 10-20 fold increase in the power cleansing going on in your brain.  The REASON the cleaning is so effective during this time is that the glial cells shrink in NREM sleep which allows he cerebrospinal fluid to clean out the gunk from that day’s neural activity. (p160)
  • Should you experimentally prevent a mouse from getting NREM sleep, there is an immediate increase in amyloid deposits (associated with Alzheimers) in the brain.  Put another way, wakefulness is low-level brain damage, while sleep is neurological sanitation. (p161)


Sleep Deprivation And The Body

  • A 2011 study tracked more than held a million men and women of varied ages, races, and ethnicities across with different countries.  Progressively shorter sleep was associated with a 45 percent increased risk of developing and/or dying from coronary heart disease within seven to twenty-five years. (p165)
  • A Japanese study of over 4,000 male workers over a 14 year period found that those sleeping 6 hours or less were 400 to 500 percent more likely to suffer one or more cardiac arrests than those sleeping more than six hours. (p165)
  • Part of the reason the heard suffers so dramatically under the weight of sleep deprivation is blood pressure.  Lack of sleep can pump up the pressure in the veins of your entire body. (p165)
  • Daylight savings is a “global experiment” in which 1.5 billion people are forced to reduce their sleep by one hour or less for a single night each year.  In the Northern Hemisphere, the switch to daylight savings time in March results in most people losing an hour.  In tabulation millions of hospital records, we find a frightening spike in heart attacks the following day.  The opposite happens when people gain an hour. (p169)
  • Does diabetes impair your sleep, or does short sleep impair your body’s ability to regulate blood sugar, thereby causing diabetes? In this experiment it was found that formerly healthy participants were 40 percent less effective at absorbing a standard dose of glucose, compared to when they were fully rested. (p171)
  • Do we eat more when sleeping less? In this experiment, the same individuals ate 300 calories more each day (1k calories per week) vs when they were getting a full night’s sleep. (p173).  Note on p175 – we don’t eat more when we are sleep deprived because we burn extra calories to stay awake.
  • A recent discovery has been made that sleep loss increases levels of circulating endocannabinoids, which are chemicals produced by the body that are very similar to the drug cannabis.  Like marijuana use, these chemicals stimulate appetite and increase your desire to snack. (p174)
  • In an experiment comparing patterns of brain activity when participants are shown “good” food vs “bad” food, found tat supervisor regions of the prefrontal cortex required for thoughtful judgements and controlled decisions are silenced in their activity by lack of sleep. The more prial deep-brain structures that drive motivations and desire were instead amplified in response to the food images – so high calorie foods became significantly more desirable to the sleep deprived, by 600 extra calories on average. (p176)
  • Evidence for the effect of sleep loss on obesity has been gathered over the past 30 years, back in 1940 when humans had close to 9 hours sleep a night, obesity was less than 5%, and continues its reverse trajectory through time with now the average sleep being 6.5 hrs and the obesity rate at 35%. (p177)
  • When losing weight, the amount of sleep you get affects the type of weight you lose.  If 6 hours or less, 70% of the weight lost is muscle, when sleeping correctly, 50% of the weight lost is fat, whilst preserving muscle. (p178)
  • Take a group of lean, health young males in their mid-twenties and limit their to five hours sleep for one week.  The hormone blending effect ages the man by 15 years in terms of testosterone virility. (p179)
  • Routinely sleeping less than six hours a night results in a 20 percent drop of follicular-releasing hormone in women. (p179)
  • Women who work erratic hours were 80% more likely to suffer from issues of sub fertility. 33% higher rate of abnormal menstrual cycles too. (p180)
  • Women who do become pregnant and routinely sleep less than eight hours a night are significantly more likely to suffer a miscarriage in their first trimester, relative to those consistently sleeping eight hours or more a night. (p180)
  • The less an individual  sleeps in the week before facing the active common cold viru, the more likely it was they would be infected.  In those sleeping five hours on average, the infection rate was almost 50%, in those sleeping seven or more hours a night in the week prior, the infection rate was just 18%. (p182)
  • A study in 2002 showed that sleep profoundly impacts responses to a standard flue vaccine.  Those participants who obtained seven to nine hours sleep in the week before getting the flu shot generated a powerful antibody reaction.  Those who were sleep restricted produced less than 50 percent of the immune reaction to their well slept counterparts.  Similar results have been reported for hep A and hep B vaccines too. (p183)
  • A brief dose of short sleep can affect your cancer fighting immune cells.  One night of 4 hours of sleep can sweep away 70% of your natural killer cells vs a full eight hour night of sleep. (p184.)
  • Lack of sleep also significantly affects cancer cell progression once taken hold.  Experiments from the University of Chicago (results found when mice were injected with malignant cells and tumor progression tracked over 4 weeks).  Sleep deprived mice suffered a 200 percent increase in the speed and size of cancer growth relative to the well-rested group. (p185)
  • Not getting enough sleep when fighting a battle against cancer is like pouring gasoline or an already aggressive fire. The scientific evidence linking sleep disruption and cancer is now so damning that the World Health Organization has officially classified nighttime shift work as a “probable carcinogen”. (p166)
  • Thousands of genes in the brain depend on sleep for stable regulation.  Deprive a mouse of sleep for a day and the activity of these genes will drop by over 200%.  Like a stubborn file that refuses to be transcribed by a printer, when you don’t lavish these DNA segments with enough sleep, they will not translate their instrutinal code into printed action and give the brain and body what they need. And the effect on humans is as pronounced as it is in mice. (p187)