Last week we dove into why we sleep, the stages of sleep, and why we don’t hear about it enough or care as much as we should. (Read here, if you haven't already.) This week we take a look at different sleep types and the harm we do to ourselves, short- and long-term, by depriving ourselves of this critical restorative function.
“I’m not an early bird or a night owl. I’m some form of permanently exhausted pigeon.”
I’m not without a sense of humour. When I first saw the above meme, I laughed and shared it with my spouse, who shared it with multiple friends. The popularity of the above meme speaks volumes to the need for us to strive for better sleep. Outside of serious sleep disorders, none of us should be “permanently exhausted pigeons”, and certainly existing in this state is not a joking manner.
That said, being a “night owl” or an “early bird” are real things. We all have a chronotype, governed by our own circadian rhythm and for the most part, we all exist within a few hours window. Some of us tend to want to fall asleep a few hours later and wake up a few hours later and as such are termed “night owls”, where others operate better falling asleep and waking up earlier. Your chronotype is genetic and trying to change it is generally not possible. Extremes outside of a 2-3-hour window to go to sleep can cause an individual difficulty in living within society, as they will be rendered incapable of functioning with others and properly participating in school, work or social activities. When someone’s sleep habits become this much of an issue it is considered a circadian rhythm sleep disorder.
In order to optimize your sleep and health, it may be wise to structure your life around your circadian rhythm, if at all possible. If your work or career is flexible, starting at a time appropriate to your body could be an easy and great way to improve performance and health. To figure out what your chronotype is, there is a standard questionnaire in use.
Personally, I tend to be more of a night owl and my spouse is more of a morning person. I do my best work, my reading, and my thinking often between 9pm and midnight. My spouse on the other hand is often fast asleep by 9pm and awake by 5am. It is possible that the early sleep issues I developed and ensuing caffeine addiction could have been partially mitigated by structuring my morning and day time obligations across more days, rather than isolated and focused on just a couple that needed me to rise early.
Different Durations Needed
We know that we need different amounts of sleep at different stages of our lives, but do different people need different amounts of sleep? Probably. It’s impossible to pinpoint an exact recommendation for any one person without a detailed analysis, so evaluating your own sleep is still the best. The National Sleep Foundation set new sleep targets, widening some of the ranges.
Newborns (0-3 months): Sleep range narrowed to 14-17 hours each day (previously it was 12-18)
Infants (4-11 months): Sleep range widened two hours to 12-15 hours (previously it was 14-15)
Toddlers (1-2 years): Sleep range widened by one hour to 11-14 hours (previously it was 12-14)
Preschoolers (3-5): Sleep range widened by one hour to 10-13 hours (previously it was 11-13)
School age children (6-13): Sleep range widened by one hour to 9-11 hours (previously it was 10-11)
Teenagers (14-17): Sleep range widened by one hour to 8-10 hours (previously it was 8.5-9.5)
Younger adults (18-25): Sleep range is 7-9 hours (new age category)
Adults (26-64): Sleep range did not change and remains 7-9 hours
Older adults (65+): Sleep range is 7-8 hours (new age category)
As I discussed in part 1 of this series, I can “get by” on much less sleep than the recommendation for my age. That said, when I am more conscientious with my sleep and set sleep goals, ensuring I get 7 hours, I feel better. Beyond 7 hours I struggle and will often feel more sluggish with the added rest. The National Sleep Foundation recommends asking yourself these questions in order to ascertain if you are getting enough sleep:
Are you productive, healthy and happy on seven hours of sleep? Or does it take you nine hours of quality ZZZs to get you into high gear?
Do you have health issues such as being overweight? Are you at risk for any disease?
Are you experiencing sleep problems?
Do you depend on caffeine to get you through the day?
Do you feel sleepy when driving?
These are questions that must be asked before you can find the number that works for you.
The Damages of Sleep Deprivation
According to the largest systematic review and meta analysis of the literature encompassing almost 1.4m total participants, the “consensus” is in; short sleep duration increases all cause mortality.i Sleeping too much seems to, as well, however if someone is chronically sleeping too much that could be a sign of other issues. Lack of sleep has been associated with many other health risks. Many of the greatest challenges facing our health are strongly linked to sleep deprivation.
Lack of Sleep and the Brain
Lack of Sleep Deactivates the Glymphatic System
As I discussed in Part 6 of the hormesis series, lack of sleep, or specifically deep REM sleep, deactivates the glymphatic system.ii Proper function of the glymphatic system, our internal system that deals with junk removal in our central nervous system (CNS), is critical in both the prevention and development of various neurological and CNS diseases.iii
Lack of Sleep and Alzheimer’s
Although it is not yet known if it is causative, poor sleep quality in one’s 40s, 50s, and 60s is a significant risk factor for the development of Alzheimer’s disease.
“Walker and his colleagues, including graduate student and first author Joseph Winer, found that adults reporting a decline in sleep quality in their 40s and 50s had more beta-amyloid protein in their brains later in life, as measured by positron emission tomography, or PET. Those reporting a sleep decline in their 50s and 60s had more tau protein tangles. Both beta-amyloid and tau clusters are associated with a higher risk of developing dementia, though not everyone with protein tangles goes on to develop symptoms of dementia.”
While hydrogen water has been indicated in aiding with amyloid-beta induced cytotoxicityivv and blocking the expression of tau proteins,vivii both are early findings primarily in rodents, and it is always best to take as many practical precautions as possible. Getting adequate sleep is logically preferable to a considerable degree than justifying lack of sleep with the use of hydrogen water.
Lack of Sleep and Depression
Lack of sleep and depression are very strongly correlated and could perhaps be bi-directionally causative.viii Depression can lead to an inability to sleep, and poor sleep can exacerbate depression.ix Perhaps one of the reasons why sleep can contribute to the formation or progression of depression has to do with inflammation. Depression has shown to increase levels of inflammation in the brain,x and increased inflammation has been linked with an increased risk of developing depression.xixii Further, loss of sleep is well documented in raising inflammatory markers in otherwise healthy subjects.xiii In some cases, the use of anti-inflammatory drugs has aided in the treatment of depression, and teams experimenting in this route have hypothesized that higher levels of inflammatory cytokines drive increased fatigue,xiv which could further exacerbate sleep issues, and depression.
Interestingly, a 2018 study with 18 human participants found that sleep loss increased social withdrawal and loneliness.xv Loneliness and a decreased sense of social purpose are very strongly tied to depression.xvixvii
Lack of Sleep and Impairment
One of the reasons why many high performers try to limit their sleep is this false belief that it will improve their personal, intellectual or professional improvement and progress. From a scientific standpoint this is contrary to the evidence. One study showed that pulling an “all nightery” reduced information retained in memory by 40%.xviii Further, there is evidence suggesting that even moderate sleep deprivation impairs your cognitive and motor skill function as much as alcohol-induced intoxication at legally intoxicated levels.xix
Having previously been involved in breathalyzer fuel cell technology, I could write a fairly long series on the issues with directly correlating a BAC% to impairment. That said, for most people, most of the time 0.05% will lead to impairment as your BAC% will wildly change from day to day due to a myriad of factors, even given a constant alcohol consumption. I do some of my best writing and reading when slightly impaired, blowing around 0.01-0.02, however, once I exceed intoxication thresholds my thinking, writing and retention of what I am reading dramatically decreases. By impairing yourself through sleep function, it is potentially impairing the function of the most important aspects of what allows you to perform at a high level.
In addition to the deleterious effects to our brain, lack of sleep has significant ramifications on our body, particularly our metabolic health, but extending to numerous other facets. Weight gain has been strongly linked to shorter sleep duration,xx and subjecting participants to just a single week of impaired sleep (4 hours per night) significantly impacted their glucose tolerance and raised their cortisol (stress) levels dramatically.xxi This could lead to doctors classifying you as prediabeticxxii, suggesting that modifying them, i.e. improving sleep function, would improve the state towards healthy.
Lack of Sleep and Biological Risk Factors of Aging
As discussed above, lack of sleep increases inflammatory markers, which are a strong indicator of accelerated aging and risk for developing age related conditions.xxiii Lack of sleep has also been linked to increased levels of oxidative stress,xxiv which also leads to disrupted sleep,xxv leading to a vicious pathophysiological loop amplifying the damage of both lack of sleep, and oxidative stress.xxvi Increased levels of oxidative stress, or dys-homeostasis of the redox status within our cells, is also considered one of the “pillars” of why we age and develop conditions of aging.xxviixxviiixxixxxx
Another marker often discussed in terms of aging and degenerative conditions of aging is telomere length shortening, which has also been linked to sleep deprivation,xxxixxxii even when studied in children.xxxiii I remain skeptical of the long-term implications of this, as telomere length can rebound, with research showing meditation, mindfulness and the purported “anti-stress” benefits from it significantly increasing telomere length.xxxiv Further, a snapshot of telomere length has been shown to have no correlation with life expectancy even in centenarians and those in advanced age, with the only markers statistically accurate in predicting mortality being those associated with inflammation.xxxv
Sleep deprivation has also shown to have negative consequences for testosterone in menxxxvixxxviixxxviii, and virility, xxxixxlxli although, so does stressxliixliii, and it is not known if the negative consequences are long-term or can be abated with proper rest.
Gut Bacteria Circadian Rhythm
One of the hottest topics in research is currently the effects of our microbiome on various conditions and overall health. In 2016, the Department of Defense issued a $7.5m grant to CU-Boulder to study the effects of sleep duration on the microbiome in humans, mice, and rats.xliv While I am not aware of any of the results being published from this ongoing project, teams from other institutions have recently begun publishing papers linking adequate sleep with a more rich and diverse gut microbiota,xlv as well as the possibility that improving gut microbiota could assist in sleep apnea.xlvi Another recent review discussed the microbiome, circadian rhythms, and depression.xlvii