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Sleep Psychologist Shares the Effects of Poor Sleep

Hayley Dawes
12 April 2023

Making sure you get enough sleep every night is vital for your physical and mental health. It’s extremely important to get enough hours of sleep every day if we’re to have enough energy to go about our daily routines and tasks.

Research has shown that adults are supposed to get between 7-9 hours of sleep every night in order to function their best. However, it’s not just about getting enough hours. Your sleep quality is equally significant – you need to be comfortable, and you need to have enough REM (Rapid Eye Movement) sleep, which is when the brain becomes more active, and the body is most relaxed.

Sleep psychologist and expert Dr Katherine Hall has shared the shocking effects that lack of sleep (less than 6 hours every night) has on our bodies. Using “Sleep Deprived Sally,” the shocking visuals show what happens to our bodies if we continue to get less than 6 hours of sleep a night.


Fully rested 

If you’re getting enough sleep every night, you’ll see it on your face – your skin will be full of colour, your eyes will be bright, and you won’t have apparent bags under your eyes.

24 hours

You won’t experience any major health complications from going 24 hours without enough sleep, but you may see dark circles under your eyes, or they might be puffy. Some people experience increased food cravings, anger, irritability, drowsiness, fatigue, and decreased alertness.

Three days

Anything more than 24 hours and your symptoms are likely to start intensifying as your body starts to crave sleep. You might even start to experience microsleeps – this is when your body falls asleep for 30 seconds without you even realising it.

Your cognitive performance is massively impaired – and this will affect your decision-making skills, memory, and reaction time. On top of these, you will also have physical symptoms such as extreme fatigue, increased inflammation, and a lowered immune system.

Four days

After four days you’re extremely sleep deprived, and it gets harder for you to stay awake. Hallucinations are common at this stage; you might start to hear, see, or feel things that aren’t really there, as well as having increased fatigue, irritability, and stress.

Five days

The amount of microsleeps you have will start to intensify, and your hallucinations might turn into delusions, illusions, and disordered thinking. All the other physical symptoms will continue.

Six days

If you go six days with deprived sleep, your urge to snooze will likely be unbearable, and your perception of reality will be impaired and distorted. According to Dr Hall, you might not be able to accurately perceive and process information, which could result in a state of psychosis.

Causes of sleep deprivation

Sleep deprivation is caused by consistent lack of sleep or reduced quality of sleep. Getting less than 7 hours on a regular basis can eventually lead to health consequences that affect your whole body.

Your body needs sleep, just as it needs air and food to function at its best. During sleep, your body heals itself and restores its chemical balance. Your brain forges new thought connections and helps memory retention. Without enough sleep, your brain and body systems won’t function normally.

Stimulants, such as caffeine, aren’t enough to override your body’s profound need for sleep. In fact, these can make sleep deprivation worse by making it harder to fall asleep at night.

Signs of sleep deprivation include:

  • Excessive sleepiness
  • Frequent yawning
  • Irritability
  • Daytime fatigue

Central nervous system

Sleep is necessary to keep your central nervous system functioning properly, but insomnia can disrupt how your body usually sends and processes information. While you sleep, pathways form between nerve cells (neurons) in your brain that help you remember new information you’ve learned. 

Sleep deprivation negatively affects your mental abilities and emotional state. The signals your body sends may be delayed, and this can compromise decision-making processes and creativity.

What is microsleep?

During episodes of microsleep, you’ll fall asleep for a few to several seconds without realising it. Microsleep is out of your control, and it can make you more prone to injury in some work situations.

Immune system

Throughout your sleep, your immune system produces protective substances like antibodies, to fight off bacteria and viruses. Sleep deprivation prevents your immune system from building up its forces. If you don’t get enough sleep, it tends to take you longer to recover from illness.

Respiratory system

Obstructive sleep apnea (OSA), which is a night-time breathing disorder, can interrupt your sleep and lower sleep quality. As you wake up throughout the night, this can lead to sleep deprivation, and more vulnerable to respiratory infections like flu.

Digestive system

Sleep deprivation is another risk factor towards becoming overweight and obese. Sleep affects the levels of two hormones, leptin and gherlin, which control feelings of hunger and fullness:

Leptin – tells your brain that you’ve had enough to eat.

Gherlin – an appetite stimulant.

A lack of sleep can make you feel too tried to exercise, which results in reduced physical activity and weight gain. It also causes your body to release less insulin after you eat (insulin helps to reduce blood sugar levels). 

Cardiovascular system

Sleep affects processes that keep your heart and blood vessels healthy, including those that affect your blood sugar, blood pressure, and inflammation levels. People who don’t get enough sleep are more likely to get cardiovascular disease.

Endocrine system 

Sleep deprivation can also affect growth hormone production. These hormones help the body build muscle mass and repair cells and tissues, in addition to other growth functions. The pituitary gland releases growth hormone throughout the day, but getting enough sleep and exercise also helps the release of this hormone.

How to prevent sleep deprivation

The best way to prevent sleep deprivation is to make sure you get enough good sleep. As well as making sure you get at least 7-9 hours of sleep every night, try to maintain good sleep hygiene:

  • Limiting daytime naps
  • Stop drinking caffeine after 2pm
  • Going to bed at the same time every night and waking up at the same time every morning
  • Spending an hour before bed with a relaxing bedtime routine, such as taking a hot bath, reading, or meditating
  • Restrict use of electronic devices before going to sleep
  • Regular exercise
  • Avoid heavy meals late in the evening