How Sleep Deprivation Rewires The Brain

24 hours without sleep. 3 cups of coffee. The lack of sleep is catching up to your brain as you put down strokes of ink on your Biology test, though you may not realise it. Maybe you can recall simple facts, but you’re having trouble focusing on the essay questions. Even after the test, you feel more irritable than usual, and you can’t quite capture anything your teacher is saying.

If this seems familiar to you, then you’ve experienced sleep deprivation. Although in this case, sleep deprivation may only affect you for a day, extensive sleep deprivation can cause memory impairment and possibly contribute to a higher risk of Alzheimer’s disease (Suni & Vyas, 2023). Sometimes, it may feel like sleep is a necessary sacrifice to gain a prideful test score, but it impacts the brain (and thus your behaviour) in more ways than one.

What Makes Us Sleep?

Well, first of all, what pushes us to sleep? Throughout the day, the brain’s cells are constantly active and use up energy, producing waste products. One of them is called adenosine, a neurotransmitter that binds to adenosine receptors in the brain, urging us to feel sleepy (Summer, 2022). Oftentimes, people use caffeine-containing drinks such as coffee to combat sleepiness. Caffeine binds to adenosine receptors in place of adenosine, decreasing the effect of adenosine in promoting sleepiness (Summer, 2022). 

In conjunction with adenosine, the circadian rhythm controls the release of hormones such as melatonin in response to light and dark exposure (Yale School of Medicine, 2023). As the night comes, and there is less light in the environment, melatonin is secreted to induce sleepiness, while also lowering your body temperature in preparation for sleep (Gandhi et al., 2015).

What Happens Without Sleep?

The build-up of adenosine and other waste products throughout the day cannot be broken down due to lack of sleep. Sleep causes an increase in the activity of the glymphatic system, which flushes away these toxic byproducts with cerebral fluid. The accumulation of such byproducts is thought to increase the negative symptoms of sleep deprivation, such as inability to focus, irritability, and fatigue (Aguirre, 2015).

The absence of sleep also means the absence of memory consolidation in the brain. Memory consolidation is when short-term memories are stored in long-term memory in the hippocampus, which mainly occurs during sleep (Klinzing et al., 2019). Therefore, without it, all information studied will not be retained in long-term memory; rather, it will only be remembered for a limited amount of time.

Another brain structure affected by sleep deprivation is the amygdala, which is mainly linked to emotional regulation and threat perception. When sleep deprived, the pre-frontal cortex (PFC), the control centre of the brain, is unable to regulate the amygdala, which causes it to become overreactive, and in turn causes us to become more irritable and sensitive (van der Helm et al., 2010).

In severe cases, the cumulative effect of sleep deprivation is linked to increased chances of strokes, hypertension, depression, and obesity (Colten & Altevogt, 2006).

Is An All-Nighter Ever Worth It?

So, understanding that sleep deprivation hinders our memory and affects our mood, is an all-nighter ever worth it? While it most certainly doesn’t benefit us, sometimes, there are not enough hours in the day, causing us to replace our time of rest with study. Although doing it once in a while might not have a detrimental effect (so long as you get a good night's sleep right afterwards), it doesn’t benefit your long-term understanding of your studies either. Therefore, it is advised to keep all-nighters to a minimum, and instead aim for a full night’s rest to consolidate your memory and understanding of your studies.

References

Aguirre, C. (2015). What would happen if you didn’t sleep? [YouTube Video]. In YouTube. https://www.youtube.com/watch?v=dqONk48l5vY

Colten, H. R., & Altevogt, B. M. (2006). Extent and Health Consequences of Chronic Sleep Loss and Sleep Disorders. Nih.gov; National Academies Press (US). https://www.ncbi.nlm.nih.gov/books/NBK19961/

Gandhi, Avni V., Mosser, E. A., Oikonomou, G., & Prober, David A. (2015). Melatonin Is Required for the Circadian Regulation of Sleep. Neuron, 85(6), 1193–1199. https://doi.org/10.1016/j.neuron.2015.02.016

National Heart, Lung, and Blood Institute. (2022, March 24). What are sleep deprivation and deficiency? National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health/sleep-deprivation

Summer, J. (2022, June 7). Adenosine and Sleep. Sleep Foundation. https://www.sleepfoundation.org/how-sleep-works/adenosine-and-sleep

Suni, E., & Vyas, N. (2023, July 18). How lack of sleep impacts cognitive performance and focus. Sleep Foundation. https://www.sleepfoundation.org/sleep-deprivation/lack-of-sleep-and-cognitive-impairment

van der Helm, E., Gujar, N., & Walker, M. P. (2010). Sleep Deprivation Impairs the Accurate Recognition of Human Emotions. Sleep, 33(3), 335–342. https://doi.org/10.1093/sleep/33.3.335

Yale School of Medicine. (2023). Good Sleep Recipe. Medicine.yale.edu. https://medicine.yale.edu/internal-medicine/pulmonary/news/national-sleep-week/good-sleep-recipe/