Four ways sleep deprivation affects your brain and your body

Four ways sleep deprivation affects your brain and your body

Sleep is one of the unsung heroes of health, with serious consequences when we don’t get enough. Our experts explain what happens when you’re sleep deprived and share their tips to better sleep.

Along with diet and exercise, sleep is one of the three key pillars of health,. But while we often discuss food and physical fitness, sleep gets far less focus. After all, a little tiredness didn’t hurt anybody, right? Wrong!

Inadequate sleep affects an estimated 7.4 million Australian adults, costing our economy over $45 billion annually.

Lack of sleep – whether it’s due to working late hours, social commitments, or sleep disorders like insomnia – not only makes you groggy and cranky, but it can also put your overall health at risk.

On World Sleep Day, Prerna Varma and Hailey Meaklim, PhD researchers in the RMIT Sleep Lab, explain just what happens to your brain and body when you are sleep deprived.

1. Your cognitive performance diminishes

You need sleep to recharge your brain. Being tired and not sleeping well disrupts genes that govern circadian rhythm, effectively reducing your ability to perform a task.

It also affects your memory and your ability to retain information. Lack of sleep reduces activity in your hippocampus – the memory centre of the brain. So you might pull an all-nighter to study for an exam, but forget details on the day because your hippocampus didn’t encode those memories.

Even one night of partial sleep deprivation impacts your executive functioning. In brief, sleep loss can impair attention and concentration, reducing your capacity for reasoning and problem solving.

2. Your reaction time is reduced (and your risk of accidents increases)

Have you every decided to stay awake late into the night to complete an assignment, but woken up the next morning with only 10 sentences on your screen? That’s probably because your body experienced “microsleeps”, brief episodes of sleep while you are awake.

Microsleeps usually occur when you are sleep deprived (due to a build-up of homeostatic sleep drive), getting longer until you get full sleep. This prevents you from being alert and reduces reaction time, sometimes with dire consequences.

More than one Australian dies every day due to drowsy driving or industrial accidents related to sleep deprivation. Sleep loss often results in reduced awareness of the environment and situations.

3. Your mood is disturbed (and so are your emotional responses)

Grumpy, cranky, tired or just plain annoyed after a bad night of sleep? You are not alone!

Regular sleep loss can increase negative mood states, which basically means you might feel more irritable. It can also lead to problems with relationships.

In fact, depression is overrepresented in people with sleep disorders, and insomnia is a risk factor for developing or recurring depression. Treating sleep problems can help with reducing depression and its symptoms.

That’s not all! Sleep deprivation not only affects your mood, but also your ability to interpret and understand emotional signals.

For instance, after one night of sleep deprivation, participants in a study had trouble distinguishing whether facial expressions were threatening or non-threatening. Sleep deprivation can impair the central and peripheral nervous system, making you perceive others as threatening.

4. You risk developing serious health problems

Sleep loss can put you at risk for heart disease, high blood pressure, diabetes, obesity and several other chronic medical conditions. A greater degree of sleep deprivation is possibly associated with greater adverse effects on health.  For example, sleep loss leads to an increase in ghrelin levels, a hormone responsible for stimulating appetite.

There is also a relationship between shorter sleep time and impaired glucose tolerance, a key issue in diabetes. Large population studies indicate increased risk of heart attacks and strokes related to sleep loss. Poor sleep is associated with lower life expectancy. 

15 March 2019


Woman waking up happily

So, sleep is the underappreciated hero that everyone needs more of! But how to get a better night’s sleep?

1. Know thy magic number

Every age group has different sleep needs. The National Sleep  Foundation provides some guidelines on the recommended sleep duration for your age. But sleep needs differ between individuals so keep in mind that you may need a little more or less than the average.  

2. Have regular wake-up times

Work, social commitments, mobile screens, social media and TV shows push our bedtimes on a regular basis. Before you know it, 11pm becomes 1am and then it’s 2am over the weekends and we start sleeping in much later. Together these can throw our circadian rhythms out of whack!

To have better sleep, go for a more consistent bed and wake time seven days a week (yes, even on weekends!) to anchor your circadian rhythm and help your body clock know when to be awake and when to be asleep.  

3. Make your bed a sacred space for sleep

It’s not the place to stream TV shows, watch videos, upload pictures or do a lot of thinking or worrying! Think Psychology 101 and classical conditioning here. The relationship we want in our heads is: bed = sleep.  

This is a sleep strategy we call stimulus control. Limit the bedroom to sleep and sex, so your brain knows that when you are in bed, it is time for sleep!

4. A4. Avoid napping

If you often find yourself unable to sleep at night and take naps to compensate, then avoid sleeping during the day.

It can interrupt your night-time sleep by decreasing your homeostatic sleep drive (kind of like having a snack before your main meal can reduce your hunger)!

5. Know that you can’t exercise yourself to sleep

Exercising is good for sleep overall, but too close to the bedtime and it might just wake your brain and body up! It’s counterintuitive, as people often think if they are not tired for sleep, they should do more exercise.

Exercise and having a healthy routine during the day is important but avoid doing any stimulating activity close to bedtime.

6. Avoid stimulants and heavy meals

Too close to bedtime and they can interfere with your body clock. Avoid eating big meals and drinking coffee or alcohol at least three hours before bedtime.

Steer especially clear of caffeine, which has a half-life of three to five hours. So if you have a coffee at 5pm, you may still have 50% of the caffeine in your system at 10pm.  

7. Get the right light exposure at the right time

Get plenty of light and sunshine in the morning and avoid blue light from mobile devices and LED lights at night.

Blue light from devices delays the release of your hormone of darkness, melatonin, which helps you get sleepy. Getting your light right helps your body clock regulate day and night naturally.

8. Create a buffer zone between awake and asleep

We can’t turn on sleep like we flick on a light switch! Our brains and bodies need some wind-down time to let go of our day and help us transition to sleep.

Winding down for an hour or so before bed with some relaxing activities like reading a book or some gentle yoga can help. 


See the Australian Sleep Health Foundation for more information to help you get sleeping better. If none of these sleep tips seem to help, speak to your GP and consider getting a referral to see a sleep specialist.

Sleep specialists such as sleep physicians and sleep psychologists specialise in treating sleep disorders, like obstructive sleep apnoea and insomnia, and there are effective treatments available to help you get a better night’s sleep.


Prerna Varma and Hailey Meaklim are PhD candidates in the School of Health and Biomedical Sciences. They are also chairs of Insomnia and Sleep Health for the Australasian Sleep Association, the peak scientific body in Australia and New Zealand representing clinicians, scientists and researchers in sleep. 

15 March 2019


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RMIT University acknowledges the people of the Woi wurrung and Boon wurrung language groups of the eastern Kulin Nation on whose unceded lands we conduct the business of the University. RMIT University respectfully acknowledges their Ancestors and Elders, past and present. RMIT also acknowledges the Traditional Custodians and their Ancestors of the lands and waters across Australia where we conduct our business - Artwork 'Luwaytini' by Mark Cleaver, Palawa.