Why is sleep necessary for good mental health?

Jason Brien.

Do you constantly feel like the walking dead going day in and day out with little to no sleep? When your head does finally hit the pillow, do you find that your brain has other plans and wants to stay up all night analysing everything that happened throughout the day and finding new and different ways to make you feel less about yourself? If so, then you are not alone. Humans need to sleep for a reason because if we didn’t then evolution would have stamped it out generations ago. Sleep to us humans is as vital as eating food, drinking water and breathing oxygen. Sleep and mental health go both ways. Some psychiatric disorders cause insomnia and insomnia causes some psychiatric disorders. With this in mind, let us look at some of the ways our mental health can suffer as a result of a lack of sleep.

We become more susceptible to stress;

The more tired we are, the more effort everything becomes and so, like our immune system under stress, our brains find it harder to build immunity to stress. When we are chronically tired our brains lack the energy to properly appraise external events (stressors). What this means is, our ability to refrain from imbuing stressors with negative significance decreases significantly and so the amount of stress we experience increases. Obviously, the more stress we experience, the harder it is to sleep and so continues the sleep/stress cycle. This cycle can be very, very difficult to overcome and so many people, rather than trying to reduce the stress in their lives, may resort to prescription sleep medication or drugs and alcohol to try and break the cycle. This method inevitably fails and can worsen the sleep/stress cycle.

Sleep medication can be successful but its usage must always be closely monitored by a licensed and accredited medical professional. In saying this though, sleep medication alone will not break the cycle as mentioned just previously. It is important to learn the vital skills necessary to both manage and reduce stress. Without the ability to control how many stressors we imbue with negative significance we will never gain the upper hand and so we are unlikely to ever break the sleep/stress cycle. Talk therapies and mental health professionals can also help you to manage and reduce stress by teaching you appropriate strategies whilst also being the sounding board you can release all of your frustrations to. Ultimately, the less that is swirling around in your head, the less your brain has to feed off and so hopefully the better you will sleep.

We become more susceptible to depression;

The common belief is that depression causes sleep problems but research has shown that a lack of sleep can cause depression. Depression either causes a person to not sleep at all (or sleep very little) or causes them to sleep too much. Obviously sleeping too little can cause problems but can sleeping too much cause problems also? This depends on how one classifies a problem. If you are sleeping too much and your over sleep is significantly affecting your social, familial and occupational functioning, then over sleep is a ‘problem’. The thing is though, sleep is our body’s way of telling us to slow down. Sleep is our body’s way of providing time to process things.

Many, many people will find that they require a lot of sleep and that excess sleep significantly improves their mental health even though it may negatively affect their external responsibilities (being friends, going to work, etc). People who are diagnosed with depression may feel that they cannot engage in long periods of sleep or rest because too much sleep is perceived so negatively. These people may find then that they actively prevent themselves from sleeping too much which will just exacerbate their depression. They may also feel immense guilt or shame for sleeping too much and so ‘ignoring’ their external responsibilities which again worsens their depression.

Our moods become much more labile;

Do you become grumpy and irritable when you are tired? Do you find that when you are tired you cry more than normal or experience other atypical moods and emotions? Researchers have shown that a lack of sleep increases our susceptibility to negative moods and emotions such as anger, sadness, frustration and irritability. The amygdala is the emotional control centre of the brain and a lack of sleep significantly reduces its ability to ‘filter out’ negativity. Some studies have demonstrated that people with reduced amygdala function as a result of a lack of sleep have 60% more activity in their amygdala when shown negative images compared to the participants who were not sleep deprived.

The researchers in the aforementioned study also discovered that sleep deprivation had disrupted the connection between the amygdala and the medial prefrontal cortex. The medial prefrontal cortex itself regulates amygdala function. The researchers therefore concluded that sleep deprivation appears to cause the amygdala to overreact to negative stimuli because it becomes disconnected from brain areas that normally moderate its response. Sleep deprivation also negatively affects other regions of the brain which are not directly related to emotions but a by-product of their inefficiency could indirectly cause mood problems (i.e., sleep deprivation negatively affects the hippocampus which is responsible for storing memories > becoming irritable, frustrated or angry because of atypical forgetfulness).

Our mental boundaries become blurred;

If you have ever gone without sleep for several days, you may find that you suddenly start hearing noises or seeing things which don’t exist in reality (i.e., hallucinations and other perceptual distortions). You may also experience flight of ideas – thoughts and conversation topics have no clear direction and so follow no normal temporal sequence. You may also start believing in things which you would not normally believe in were you rested (i.e., “Is that man sitting opposite me on the train secretly planning to abduct me”)? This is the basis of paranoia – making loose connections between otherwise unconnected events, thoughts, etc.

Obviously then, if a lack of sleep can cause such pronounced perceptual problems in ‘normal’ people, imagine the effect that a lack of sleep can have for people diagnosed with conditions such as schizophrenia, psychosis, etc. People diagnosed with such conditions must be much more mindful and diligent about getting adequate sleep whilst also ensuring that they continue to take any prescribed medications. When our mental boundaries have become blurred, we need to engage in reality testing more often. Reality testing requires us to test our perceptions to ensure that they exist in reality. Reality testing can be as simple as asking another person if they heard the same noise or saw the same thing that you just did.