Sleep deprivation means getting an insufficient amount of sleep. The average adult requires between seven to nine hours per night for optimal functioning.1 Sleep is beneficial to both the functioning of our brains and bodies. Conversely, sleep deprivation or non-restorative sleep can have a myriad of negative effects, particularly on our cognitive functioning. Lack of sleep effects can include memory and judgment impairment, mood swings, and sleep deprivation headaches. Other common signs of sleep deprivation may be clumsiness, and weight gain or weight loss. Chronic partial or total sleep deprivation can seriously impact your physical and mental health.
Partial sleep deprivation or sleep restriction is the condition of sleeping an insufficient amount of time to feel rested. Mild sleep restriction often goes unnoticed until a sleep deficit builds up. Lack of sleep effects on your body are much easier to identify than the effects on the brain. Sleep deprivation’s effects on the brain are arguably more dangerous and potentially life-threatening.2
The first symptoms of sleep deprivation tend to be the impairment of cognitive functioning. In the short term, sleep deprivation can affect your stress hormones, disrupting your cognition and destabilizing your moods.3 For some, this can cause more volatile and intense reactions to everyday life stressors or situations. It also can make you irritable and angry. Partial sleep deprivation has also been found to affect your ability to concentrate and pay attention to detail. A popular theory is that partial sleep deprivation causes slower and impaired thinking in the prefrontal cortex. The prefrontal cortex controls what is known as higher function activities, such as language, executive function, and creativity. When you are sleep-deprived, there is an over-exertion of the prefrontal cortex, resulting in impaired concentration, alertness and reduced coordination.4 If partial sleep restriction becomes chronic, its symptoms may start to resemble those of total sleep deprivation.5
Total sleep deprivation is typically classified as going at least one full night without sleep.6 Your ability to complete tasks with speed and accuracy begins to decrease soon after this. Sleep deprivation can affect your short- and long-term memory.7 Some studies suggest that memory is negatively impacted by impaired synaptic plasticity in the hippocampus.
There are generally thought to be five stages of sleep deprivation, which, as they progress, have growing repercussions. Stage 1 of sleep deprivation is one night or 24 hours without sleeping. At this point, you display many of the same symptoms as those with partial sleep deprivation. Stage 2 is generally categorized as 36 hours without sleep. This is when your ability to learn new information, memory, reaction time, and your ability to make decisions will become substantially weakened. The next stage, Stage 3, or going 48 hours without sleep, is when you enter a more intense stage of sleep deprivation. During this stage, you are more likely to experience “microsleeps.” Microsleeps are the occurrence of falling asleep unintentionally from anywhere between a fraction of a second to 15 seconds.8,9 Along with the previous symptoms of sleep deprivation, you may start to experience intense anxiety, hallucinations, or depersonalization. Stage 4, or 72 hours without sleep, comes with a higher likelihood of depersonalization, delusions and disordered thinking. Finally, Stage 5, being awake for four days or 96 hours, may cause intense feelings of delusion also known as “sleep psychosis,” in which your brain cannot accurately interpret reality.10 Ongoing sleep deprivation after this is very dangerous and can have serious, and possibly fatal, health repercussions.
There is no conclusive study as to whether lack of sleep causes irreversible brain damage in humans. Some studies in mice have shown that sleep deprivation has killed brain cells, but whether this is also true for humans is unknown.11 Short-term or partial sleep deprivation is not thought to have long-lasting effects on brain functioning and can generally be counteracted with a regular sleep schedule.
There is no conclusive evidence that lack of sleep kills brain cells in humans. Identifying the effects of sleep deprivation on brain functioning is a complex and ongoing study. Sleep allows our brains to rest and restore our neurons and neurotransmitters, and it is hypothesized by some that long-term sleep deprivation may cause our neurons to degenerate and have difficulty communicating with one another.12
Sleep deprivation can disrupt the normal functioning of your brain and body. For many people, lack of sleep affects their mood, ability to focus, and handle life stressors. It can also impact your memory and have serious effects such as depression and psychosis. Additionally, sleep deprivation can negatively impair your body’s ability to fight off infection, and may increase the likelihood for heart disease and obesity.13
Although it may take time, it is possible to fully recover from sleep deprivation. Getting enough sleep and having a regulated sleep schedule can help you to restore your sleep deficit.
Sleep anxiety is when feelings of stress and anxiety surround going to sleep. It is a form of performance anxiety. Similar to treating insomnia, there are many natural sleeping remedies as well as medications that can help reduce sleep anxiety.
© 2021 American Sleep Association.