Tuesday, 3 November 2015

Wake-up call: Sleep deprivation is bad for you

Sleep is important for a variety of reasons, such as consolidating memory and feeling awake. But did you know that a lack of sleep can lead to weight gain or depression?

Last week on my neuroscience radio show Brainwaves, we discussed some of these issues, as well as some of its unlikely therapy uses. If you'd like to listen to the full podcast of the show with fellow neuroscience undergrads Tori and Georgie, click here!

When we sleep and how much sleep we get is controlled by two systems - our wake/sleep homeostasis (i.e. if you don't get enough sleep your body makes you tired so you can catch up on the sleep you need) and our circadian clock. The clock regulates when we sleep. Ever noticed that regardless of how late you go to sleep you will wake up at a relatively similar time? That's your circadian clock telling you it's time to get up. The clock is partly controlled by light levels in our environment (it can also be controlled by food; you eat dinner, your body knows bed-time is soon). 

This graph shows how our need to sleep depends on how much sleep we have gotten the night before.

A lack of sleep can be incredibly detrimental to your health and the working of your circadian clock.  For example, sleep deprivation impairs coordination, judgement and ability to retain information. In this list we'll be looking at how a lack of sleep can negatively affect you and those around you.

1. Sleep loss can cause accidents
Sleep deprivation was listed as the major cause in some of the worst disasters in recent history. The famous 1986 nuclear meltdown at Chernobyl was attributed to the fact employees had been working for 13 hours or more. The 1989 Exxon Valdez oil spill, which spilled 258,000 barrels (38 million US gallons of oil) into an ocean inlet in Alaska was caused by the third mate of the boat allegedly sleeping at the helm of the boat, exhausted from a lack of sleep. 

More close to home, sleep deprivation is the cause of 100,000 car crashes and 1,550 car crash related deaths every year in the US. This mostly affects young drivers under 25. Numerous studies have actually found that 17-18 hours of being awake is as harmful as driving with a blood alcohol level of 0.5% - which is above the legal limit in many European countries!

Are you getting enough sleep?

2. Losing sleep can make you gain weight
Lack of sleep has been proven time and time again that it is related to an increase in hunger and appetite. According to a 2004 study, people that sleep less than 6 hours a night are almost 30% more likely to become obese than those that slept 7-9 hours. This is probably related to ghrelin and leptin - ghrelin is a peptide that stimulates appetite and hunger, leptin signals satiety and suppresses appetite.

 During sleep normally, leptin levels increase. This tells your body that you have energy for the time being and don’t need to wake up hungry in the middle of the night. Your brain does basically the opposite with ghrelin for the same result – it decreases levels, ensuring that you don’t wake up hungry. However, when you don’t sleep enough, you end up with too little leptin and too much ghrelin. Scientists think that these changes to hormone levels overnight may be a result of evolutionary processes, with the aim of keeping us alive to survive food shortages in winter – when there were longer nights and less food (long night, more leptin and less ghrelin). So, if you're on a diet.. make sure you're getting your full 8 hours of sleep a night!

3. Sleep loss ages your skin
When we don't get enough sleep, often it shows on our skin; puffy eyes and pale sallow skin are the easiest to spot symptoms. These are a result of elevated cortisol levels. Cortisol is a steroid hormone, and is also known as the stress hormone - it's produced in response to stress in those fight-or-flight situations. One study on sleep deprived individuals found that their levels of cortisol were substantially higher than those who got enough sleep. These levels also took 6x longer to decrease to normal. 

At high levels, cortisol can breakdown and deregulate the synthesis of collagen, which is an important component of connective tissue - vital for smooth skin. 

This image shows the difference in how we look after a night of sleep.
(L) the man has been sleep deprived. (R) the man is well-rested.

Acute sleep loss may play a role in treating depression 
Interestingly, research is currently underway into the effects of acute sleep deprivation on those with depression. New studies have found that acute sleep deprivation can temporarily give immediate relief from depression, with a 60% success rate! This seems counterintuitive but does actually make sense. It plays on the fact that when you pull an all-nighter, sometimes the tiredness doesn’t immediately hit you and instead you feel hyper and giggly. This phenomenon is caused partially by an alteration in the activity in our frontal cortex (which deals with reasoning and logic). 

It may be related to adenosine release. Adenosine is a protein that is important in sleep regulation – its release is increased the longer you are awake, causing you to feel tired. However, recently a beneficial side effect of its release has been found – it can alleviate depressive symptoms. So basically, stay awake and acutely sleep deprive yourself à adenosine release increases à feel tired but depressive symptoms disappear à feel giddy and happier. Unfortunately these symptoms are short term and only last until the person falls asleep, where adenosine levels get back to normal.

I hope you found this list of sleep deprivation effects interesting, and hopefully it'll encourage you to make sure you get a solid 8 hours of sleep every night!


  1. I will definitely make sure I get enough sleep after reading this!

  2. I knew most of these, but didn't know about the weight gain, although it makes sense! Very interesting post and I shall be making sure I sleep well more often :)