The Five Benefits of Sleep

Blog #2 in the series on mental and physical performance, Context: Male, 28 years old.

Note: One of the most important books on sleep out today is Why We Sleep by Matthew Walker. The contents of this post are derived from his book which you can find here. I have included page number references where possible. 

Pop culture or success culture today is pervaded by a spirit of extreme output. Whether it is Elon Musk or Jocko Willink or any number of instagram pseudo celebrities, it has become increasingly popular to suggest minimizing sleep time (<7 hours) to maximize the number of output producing hours in the day. In concept, this seems logical because no output can happen while you sleep.

And for what it is worth, there is scientific evidence that some people can operate effectively on extremely limited amounts of sleep (4-6 hours). Precisely that number is 1 in 4 million or less than 100 people in the entire United States. However, for the vast majority of us (99.999%+) that isn’t the case and it is suggested that we get between 7-9 hours, but why? 

1. Memory Consolidation and Learning Improvement - Sleep helps us record, store, and prepare for the information that we take in. This is not restricted to academic learning either with significant impact seen in physical/athletic performance as well. There was 20-40% improvement in a group of students who napped and didn’t nap when tested for memorization (page 110). 
2. Athletic Performance & Focus - Sleep also helps us achieve higher energy levels and focus. Andre Iguodala’s performance at the free throw line after nights with more than 8 hours was 9% higher (page 130). In a non-athletic setting, individuals who get between 5-6 hours of sleep have a 1.9x higher car crash risk (page 139). 
3. Repair and Recuperation - Sleep is the time when the body is able to repair itself both physically and mentally. For athletes, the chance of injury of those getting less than or equal to 7 hours of sleep is roughly double than those with 8+ hours. This same repairing mechanism also extends to other prevalent forms of disease like cancer and dementia, as this time is used to "clean out" cancerous cells and bad actors are cleaned out with cerebro spinal fluid. Additionally, Walker adds that emotional traumas can be better managed under well rested conditions. 
4. Mood Management - Sleeping sufficiently can also have an impact on your mood, with some sleep deprived cohorts seeing an increase in reactivity to negative images of 60% (page 146). Often we think of mental health as a discrete and personal imperfection, but in some cases it may just be a lack of sleep that is holding you back.
5. Weight Management - One additional benefit is that sleep suppresses the hormone ghrelin (which triggers your desire to eat) while simultaneously keeping the hormone leptin (which indicates to your brain that you are full) elevated. If levels of these hormones are imbalanced, you may still be hungry even after eating and more prone to overeating and weight gain. 

As the following list indicates, the benefits of sleep are robust and numerous.  Sleep has a material impact on wellness and wellbeing and we are still in the early stages of understanding this relationship within this blog and within the scientific community in general. Click here to learn how to measure if you are getting enough.

References:

1. Walker, M. P. (2018). Why we sleep: The new science of sleep and dreams. Penguin Books.