Why is Lack of Sleep so Bad?

Updated: Dec 26, 2020

Marta Taylor will talk about how lack of sleep can make you fat, sick and angry...amongst other things.


Now let’s talk seriously about why a lack of sleep is so bad for you and the importance of getting enough and good quality sleep.  It’s a crucial component of living limitlessly because it greatly affects your health.

There are many things going on in your body whilst you are sleeping.  In fact, your waking hours are largely dependent on the work that is done during sleep – this includes supporting healthy brain function and maintaining your physical health.


Sleep helps you to pay attention, make decisions, and be creative.  A lack of sleep or sleep deficiency alters activity in parts of the brain which may cause you to have trouble making decisions, solving problems or controlling emotions and behaviour.  Sleep deficiency has also been linked to depression, suicide, and risk-taking behavior.

Studies show that a chronic lack of sleep of less than six hours per night produced cognitive performance deficits which equalled up to 2 nights of total sleep deprivation.  Apparently, even moderate sleep restriction can impair waking neurobehavioral functions in healthy adults. (1)

In 2012, researchers identified a new maintenance system called the glymphatic system, which uses the cells’ mitochondria to remove cellular waste from the brain (2) (3).  (Mitochondria converts energy into a form that cells can use)  They found that the clear cerebrospinal fluid (CSF) in the brain is what is responsible for draining toxins from the brain and that this system is most active during sleep.

Another study by, the The National Institutes of Health show that during sleep, a particular waste product known as amyloid beta is cleared from the brain at a faster rate than when a person is awake.  Amyloid beta has been connected to Alzheimer’s disease.


Studies show that a good night’s sleep improves learning.  Evidence shows that a night of sleep results in a 20% increase in motor speed without loss of accuracy, whereas an equal amount of wake time (instead of sleeping) & then repeating the chosen exercise, showed no sign of improvement. (4)  It has been concluded that sleep restructures new memory representations and facilitates extraction of specific knowledge (5).


While we sleep, our brains process and consolidate our memories from the day.  If you don’t get enough sleep, it seems like those memories might not get stored correctly and can potentially be lost.

In short, while you’re sleeping, your brain is preparing for the next day.  It is forming new pathways to help you learn and remember information.


Sleep plays a really important role in your physical health.  Sleep encourages healthy cell division (helps prevent cancer)(6) whereas, ongoing sleep deficiency is linked to an increased risk of heart disease, kidney disease, high blood pressure, diabetes, and stroke amongst other things.

Weight Control

Sleep plays two roles in weight control.  Firstly, from a physiological perspective, sleep helps to maintain a healthy balance of the hormones that make you feel hungry (ghrelin) or full (leptin).  When you don’t get enough sleep, your level of ghrelin goes up and your level of leptin goes down.  This makes you feel hungrier than when you’re well-rested.  So when you don’t get enough sleep and your leptin levels drop you will feel hungrier and probably, crave high-calorie foods.

Secondly, from a behavioural aspect – if you’re too tired, you will probably have less energy to do exercise or go to the effort to eat well by cooking a healthy meal, instead of something that is quick and easy & probably ‘bad’ for you nutritionally.

A study of teenagers showed that with each hour of sleep lost, the odds of becoming obese went up.  A lack of sleep and sleep deficiency increases the risk of obesity in other age groups as well (7).

Insulin Levels

Sleep also affects how your body reacts to insulin, the hormone that controls your blood glucose levels.  Sleep deficiency results in a higher than normal blood sugar level.  This may increase your risk for diabetes as shown by one study that simulated the effects of the disturbed sleep patterns of shift workers on 10 young healthy adults.  After only four days, three of them had blood glucose levels that qualified as pre-diabetic. (8)


The immune system defends your body against foreign or harmful substances which relies on sleep to work at its best. Ongoing sleep deficiency can change the way in which the immune system responds and trigger an inflammatory response in the body.  At best, you may have trouble fighting infections like a common cold.  One study had researchers track over 150 people and monitored their sleep habits for two weeks.  After that period of time, they exposed them to a cold virus.  People who got seven hours or less of sleep a night were almost three times as likely to get sick as the people who got at least eight hours of sleep per night.

Bigger issues can arise as sleep loss may also cause long term changes and may contribute to the development of cardiovascular diseases and type 2 diabetes.  These two diseases are known to be linked to inflammatory responses in the body.

University of Helsinki researchers have identified genes which are most susceptible to sleep deprivation and examined whether these genes are involved in the regulation of the immune system (9). Conducted at the sleep laboratory of the Finnish Institute of Occupational Health, the study restricted the amount of sleep of a group of healthy young men to four hours per night for five days.  Blood samples were taken before and after the sleep deprivation test.  The results were compared with samples from healthy men of comparable age who had been sleeping eight hours per night for the week.

There was an increase in activity of B cells which are responsible for producing antigens that contribute to the body’s defensive reactions, but also to allergic reactions and asthma.  The amount of certain interleukins, or signalling molecules which promote inflammation, increased.  On the gene level, this was apparent in the higher-than-normal expression of the TLR4 gene after sleep loss.  C-Reactive Protein (CRP) levels were also elevated, indicating inflammation.

If you thought that a lack of sleep was just “bad luck” and you would just deal with it, then think again.  Continuous amounts of sleep deficiency will produce long term health issues that are of a serious nature

My next post – 5 sleep hacks to sleep better – will look at all the things you can implement to ensure you get a good quality sleep that will help you feel better on a daily basis, contributing to your overall health.

mt xx


  1. http://www.med.upenn.edu/uep/user_documents/VanDongen_etal_Sleep_26_2_2003.pdf

  2. http://www.alzforum.org/news/research-news/brain-drain-glymphatic-pathway-clears-av-requires-water-channel

  3. http://stm.sciencemag.org/content/4/147/147ra111

  4. http://www.ncbi.nlm.nih.gov/pubmed/12123620?dopt=Abstract#

  5. http://www.ncbi.nlm.nih.gov/pubmed/14737168?dopt=Abstract#http://occmed.oxfordjournals.org/content/60/1/10.full.pdf+html

  6. http://www.jpeds.com/article/S0022-3476%2814%2900597-6/abstract

  7. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3678519/pdf/nihms408028.pdf

  8. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0077184