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The Effects of Sleep Deprivation on Human Health

Diet & Nutrition Inspiring People


Until recently, sleep was perhaps the most under-recognized piece of the health puzzle. It’s not that it was completely ignored, but the conversation generally revolved mostly around diet and exercise. Now, we are beginning to see, more and more, the enormous role that healthy sleeping patterns play in our overall health and performance.

What happens when we sleep?

When we sleep, our body disables sensory and muscle activity and we enter an altered state of consciousness.

During sleep, the body accelerates its recovery by building tissue and restoring immune and hormone functions and removing toxins from the brain and nervous system by way of a rhythmic ‘washing’ of the brain by the glymphatic (glial + lymphatic) system.

When we are asleep, we go through several phases of sleep including those categorized by rapid eye movement (REM), and non-REM sleep.

Within minutes we enter stage one sleep, characterized by alpha and theta brain waves. After several minutes of light, stage one sleep, we enter stage two. And ‘deep sleep’ (also called slow-wave sleep) involves stage three and four. In these stages, muscle activity is inhibited, and it is harder to awaken. About 90 minutes after falling asleep we then enter REM sleep characterized by rapid, jerking movements of the eyes. In this phase, the brain reactivates (most dreaming occurs during REM sleep) and this plays an important role in learning and memory, as the brain processes and organizes information during this phase.

sleep graph

How much sleep do we need?

According to the National Sleep Foundation of the US, which convened an expert panel to evaluate optimal sleep times, the recommended amounts of sleep for various ages are1:

how much sleep do we need graph

The quality of a person’s sleep (including adequate REM and deep sleep) is also extremely important. While there is no consensus on exactly how much REM and deep sleep we require, deep sleep should account for at least 13% of total sleep duration, while REM sleep typically accounts for at least 20% of sleep in healthy people2.  

Note: There can also be significant variations between people, and while most of us probably do best around the norms suggested above, it is known that genetic variability between people exists and some thrive on greater or lesser sleep times and different sleep patterns3.

The effects of sleep deprivation on health

Both short and long sleep durations are associated with poorer health and increased mortality risk46, and while we need to be aware the correlation does not always equal causation, the evidence is consistent enough that it is highly likely that poor sleep can precipitate poor health. Conversely, illnesses and health conditions can affect sleep (through physical pain and discomfort or mental and emotional anguish) but conversely, leading to a vicious cycle.

Reviews of the evidence have suggested a link between poor sleep (either length or quality) and a range of conditions, including:

  • Chronic pain and arthritis7
  • ADHD8
  • Heart disease and stroke910
  • Reduced cognition and brain health1118
  • Dementia, Alzheimer’s and Parkinson’s disease1820
  • Diabetes2122
  • Increased inflammation23
  • Depression, bipolar disorder, and anxiety2428
  • Reduced mood29
  • Multiple sclerosis (MS)30
  • Weight gain and obesity3133

Interestingly, loss of sleep is likely to also result in a lesser desire to exercise and eat well.3435  It has, for example, been shown that partial sleep deprivation can result in people eating more, choosing to eat fattier foods that are lower in protein,36 and snack and drink more soda.37 This relationship is bidirectional, as a poor diet also likely leads to poorer sleep…and so, the cycle continues!35 On the other hand, getting adequate sleep is associated with a higher intake of fruits and vegetables.37

Sometimes sleep deprivation is unavoidable, however when it does occur it is important that we try our best to make healthy food choices in an effort to break the bidirectional poor sleep-poor diet cycle! If you feel that you are struggling to meet your nutrition needs through diet, you may like to consider a multi-nutrient supplement such as Nuzest Good Green Snack Bars as ‘nutritional insurance’ to help fill the nutritional gaps in your diet.

Nuzest recently spoke to five health experts regarding their top tips for achieving a good night’s sleep.

Here is what they had to say...


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