October 16, 2023 3 min read

Sleep deprivation normally makes one feel tired, moody, and scatterbrained. But anyone who’s ever skipped a night or several of sleep is familiar with a very different kind of side effect: feeling hyper. 


Studies indeed show that in some cases, acute sleep deprivation can excite the brain and lead to unusually good mood and high energy levels. However, while this paradoxical consequence of losing sleep may sound like a good thing, these are actually signs your brain isn’t working as it should. To understand why, keep reading.

Why Your Brain Needs Sleep

The American Academy of Sleep Medicine (AASM) and Sleep Research Society (SRS) recommend that adults get 7 or more hours of sleep each night [1]. These recommendations are based on evidence showing that sleeping less than that leads to chronic health problems. 


One consequence of not enough sleep is poor mental functioning. Sleep is known to improve memory and reduce mental fatigue. That’s because the brain reorganizes and recharges itself during sleep. It also removes byproducts of energy metabolism [2]. While we used to believe sleep was a passive process, we now know that the brain goes through different phases during sleep, all of which help maintain brain health throughout the lifespan. 

How Sleep Deprivation Amps Up the Brain

Several studies have found that sleep deprivation can cause certain brain regions to become overactive and others underactive. 


In 2013, a study led by Marcello Massimini, a neurophysiologist at the University of Milan in Italy, found that certain regions of the brain become more active the longer someone is awake [3]. The region in question is the frontal cortex responsible for complex motor taste, abstract thinking, creativity, and socializing. The excitability of this region was rebalanced once the test subject slept.


An earlier study on 15 healthy volunteers shows similar findings [4]. Using transcranial magnetic stimulation (TMS), which uses magnetic fields to stimulate nerve cells, the researchers measured motor cortex excitability after 24 hours of sleep deprivation. The study found reduced inhibition of this brain region, which they say explains why people are more likely to develop epileptic seizures when sleep-deprived. 

Why This Is a Problem

As explained, the brain needs sleep for memory consolidation and waste removal, among many other things. The longer you’re awake, the more information your brain needs to process, which can overstimulate the frontal cortex and increase energy metabolism in the brain. During sleep, the brain “prunes” synapses so you retain only important information, while waste is also removed to prevent damage to your neurons. 


Another reason why an amped-up brain can be an issue is that it can impair your judgment and impulse control. 


A study led by Matthew Walker, associate professor of psychology and neuroscience at UC Berkeley found that we tend to behave irrationally when sleep-deprived [5]. Using functional magnetic resonance imaging (fMRI), the researchers found that lack of sleep amplifies pleasure-seeking regions of the brain. When asked to give their judgment on images with pleasant scenes, the sleep-deprived group gave positive ratings compared to more neutral ones in the control group.


The conclusion of this study was that sleep deprivation makes you biased and prone to pleasure-seeking, which can spell trouble if your job requires making swift decisions and critical thinking. 


References:

  1. Watson NF, Badr MS, Belenky G, et al. Recommended Amount of Sleep for a Healthy Adult: A Joint Consensus Statement of the American Academy of Sleep Medicine and Sleep Research Society.Sleep. 2015;38(6):843-844. Published 2015 Jun 1.doi:10.5665/sleep.4716

  1. Eugene AR, Masiak J. The Neuroprotective Aspects of Sleep.MEDtube Sci. 2015;3(1):35-40.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651462/

  1. Huber R, Mäki H, Rosanova M, et al. Human cortical excitability increases with time awake.Cereb Cortex. 2013;23(2):332-338.doi:10.1093/cercor/bhs014

  1. Kreuzer P, Langguth B, Popp R, et al. Reduced intra-cortical inhibition after sleep deprivation: a transcranial magnetic stimulation study.Neurosci Lett. 2011;493(3):63-66.doi:10.1016/j.neulet.2011.02.044

  1. Gujar N, Yoo SS, Hu P, Walker MP. Sleep deprivation amplifies reactivity of brain reward networks, biasing the appraisal of positive emotional experiences.J Neurosci. 2011;31(12):4466-4474.doi:10.1523/JNEUROSCI.3220-10.2011



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