Cognitive Functions That Fails Due To Lack Of Sleep
- mentalhealthclarit
- Jan 2, 2020
- 3 min read
What Is Sleep Deprivation?
Sleep deprivation occurs when a person is not able to get enough sleep. The amount of sleep needed to feel refreshed and function well depends on the individual and varies across the ages. Getting enough sleep every night is important. Some experts also believe that sleep gives our body a chance to repair itself, so the lack of sleep can have harmful health effects.
Lack of sleep affects your mental and your physical health. It doesn’t affect only your mental functions.

The image above lists the effects of lack of sleep or sleep deprivation
I answer questions daily on Quora about psychiatric illnesses. Recently, one of my followers sent me an Ask to Answer request. What mental health function fails first due to lack of sleep? I would say Cognitive Functions are the first to fail. The information I provide on my site and on Quora are researched and based on my knowledge, qualification and experience in the field of Psychology.
When I read this question I remembered the study of the 16 year old that didn’t sleep for 11 days and 24 minutes straight as part of a sleep deprivation experiment.
The Sleep Deprivation Experiment
Back in 1965, 16-year-old high school student Randy Gardner stayed awake for 11 days and 24 minutes – that’s 264.4 hours straight.
The results of the sleep deprivation experiment
Physiological and cognitive tests began to reveal. After just two days of zero sleep, Gardner’s eyes struggled to remain focussed, he showed some signs of ataxia – an inability to repeat simple tongue twisters – and he found it difficult to identify objects based purely on touch. By day three, he became moody and uncoordinated, and by day five he started hallucinating.
From there he experienced trouble concentrating, forming short-term memories, and became paranoid, and irritable.
Findings by day 11:
“Expressionless appearance, speech slurred and without intonation; had to be encouraged to talk to get him to respond at all. His attention span was very short and his mental abilities were diminished. In a serial sevens test, where the respondent starts with the number 100 and proceeds downward by subtracting seven each time, Gardner got back to 65 (only five subtractions) and then stopped. When asked why he had stopped he claimed that he couldn’t remember what he was supposed to be doing.”
So why is sleep so important for our mental health?
There is clear evidence that sleep deprivation has a negative effect on emotion and performance. A night of restful sleep may ‘reset’ brain reactivity in order to prepare for emotional challenges the next day. Sleep has an important restorative function in ‘recharging’ the brain at the end of each day, just like we need to charge a mobile phone battery after prolonged use. Maintaining a regular sleep-wake cycle allows the natural rhythm of the body to be reset every day and therefore optimises brain functioning.
Ongoing poor sleep can be a huge risk factor for the development of major depressive disorder. The risk of feeling depressed and/or anxious (as well as worsening existing anxiety and depression) increases with the severity of insomnia.
The information I provide on my site and on Quora are researched and based on my knowledge, qualification and experience in the field of Psychology.
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