Motivation and emotion/Book/2024/Sleep and ego depletion
How does sleep affect the capacity for self-control and willpower?
Overview
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Food for thought:  Have you ever been cramming for an important exam and stayed up all night studying, only to find the next day you can barely even comprehend the questions, let alone remember a semester's worth of content? This is because your poor brain has been deprived of its much-needed reset. By denying your brain sleep, you do not retain anything you studied the night before and lose valuable processing and decision-making abilities! Next time, skip the caffeine-induced all-nighter and get a good night's rest so your brain can be at its best when you need it! |
Sleep is one of the most important parts of our day. It plays a crucial role in maintaining our overall health and well-being. Throughout the day, our brains accumulate vast amounts of information and experiences. Sleep acts as a crucial period for sorting, consolidating, and storing these memories and learned experiences, allowing us to retain and build upon them effectively. Sleep also plays a crucial role in flushing out toxins that build up during the day.
In addition to its role in cognitive functions, sleep is a time for the body to reset and restore itself. When we sleep, the sympathetic nervous system 'turns off', and the parasympathetic nervous system takes over. This shift facilitates the release of growth hormones (Zaffanello et al, 2024) that promote cell repair and tissue regeneration. This restorative process helps heal tissues, build muscle, and strengthen the immune system to prepare us for the next day.
By understanding the importance of sleep, we can start to unpack why poor sleep disrupts our daily lives and health. Over time, chronic sleep deprivation can lead to more serious health issues, including increased risk of cardiovascular diseases (Nagai et al., 2010), and weakened immune response. Recognising and addressing poor sleeping habits is crucial for both short-term and long-term health. Prioritising quality sleep is essential for optimal brain function, physical health, and overall quality of life.
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Focus questions:
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What happens in the brain when we sleep?
editSleep is an integral part of everyday life; when life gets stressful, sleep is often one of the first things to be disrupted. It is estimated that adults need between 7 and 9 hours of sleep per night to fully rest and recover from the day prior, and the younger you are, the more sleep you need. The suprachiasmatic nucleus (SCN) is the part of the brain responsible for circadian rhythms in the brain, or your sleep/wake cycle. As it gets dark, the synthesis and release of melatonin is triggered which in turn decreases the amount of neuron firing in the SCN aiding in sleep.
During sleep we go through multiple stages but can broadly be characterised into deep, rapid eye movement (REM) or light, non-REM sleep. During REM sleep is when we have dreams and your brain is most active, nearly as much as when you’re awake. There is still ongoing research to further understand why we enter this state and why our brains seem to nearly ‘turn back on’ during sleep. During early infancy and early childhood REM sleep makes up most of sleep which indicates its importance in organising and solidifying neural connections.
Key chemicals in sleep
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GABA
editGamma-aminobutyric acid (GABA) is a very important amino acid within the brain which is responsible for inhibiting signals in the brain to both cause a calming effect and permit sleep (Siegel, 2004). It blocks signals to the CNS to trigger and maintain sleep. Low levels of GABA in the brain have been linked to schizophrenia, anxiety and depression (Paine, 2011; Schür, 2016). Studies have shown that a decrease in GABA is linked to impulsivity and gambling, the mechanisms as to why are still developing (Murphy 2012; Paine 2011).
Histamine
editHistamine is a chemical in the immune system responsible for intercellular communication most thought of in allergic reactions. It is heavily involved in keeping us awake, and when made inactive by GABAergic cells causes drowsiness and sleep (Siegel, 2004, ) It also has a role in the sleep/wake cycle in which the management of different receptors can induce sleep or wakefulness depending on the receptor (Thakkar, 2011). It has been shown to link to motivation especially in food motivation in which increased levels of histamine are released in preparation for mealtimes (Torrealba, 2012).
Serotonin
editSerotonin is a neurotransmitter in the brain that plays a varied role in the brain and body. Some key roles include maintaining mood, desire, and digestion. It typically promotes wakefulness and is inactivated during sleep via GABA molecules and has been linked to inhibiting the REM sleep cycle and has a role in maintaining arousal and regulating muscle tone during sleep (Monti, 2011). Serotonin has also been implicated in a person’s ability to make good decisions however the pathway that it accomplishes this is still unclear (Homberg, 2012).
Glucose levels
editGlucose levels increase during sleep and peak during non-REM sleep stages (Knutson 2007). Variation in glucose levels has a negative impact on a person’s ability for sleep. Low glucose levels can trigger sweating and nightmares, and high blood sugar can lead to poor sleep and a harder time falling asleep (Pacheco, 2020). This means that those suffering with diabetes have a poorer sleep compared to those with normal blood sugar (Yoda et al., 2015). Disrupted sleep can lead to insulin resistance which can cause a domino effect to developing pre-diabetes and diabetes. It can be thought of as a circular relationship in that high blood sugar leads to less sleep and less sleep leads to higher blood sugar. The cyclical relationship could also be contributed to lifestyle choices, assuming those with poor sleep also make other poor lifestyle choices such as unhealthy eating habits and a sedentary lifestyle (Knutson 2007).
What is ego depletion?
editThe basis of ego depletion is that it takes energy to make decisions and have self control. This mental energy is a finite resource and when depleted it becomes much harder to make appropriate decisions and practise self control leading to decision fatigue moodiness and other 'symptoms'. "The ego is constantly working to keep the ID in check. Like any other cognitive task, the ego’s constant efforts to satisfy both the ID and the superego requires mental energy, which is limited" (D. Pilat and K. Sekoul, 2021).
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"Spoon Theory" was coined as a term to describe ego depletion. You only have so many spoons in a day (and the amount can vary day to day), different tasks take a different amount of spoons, once you're out it's very difficult to continue to complete tasks. |
Physiological causes
editSelf control and making decisions are both actions that require energy. It has been suggested that glucose the primary form of energy that these actions use. There have been studies that link glucose intake to self-control and found that blood glucose levels drop after periods of decision making and self control which then suggests that self-control can be increased by consuming glucose (Matthew T et al., 2007). This study was later questioned however other studies found that simply rinsing your mouth with a sweet beverage can increase capacity for self control (Molden et al., 2012).
Implications in real life (Motivations)
editNot sleeping depletes the energy available, lowering self-control. We make decisions that are not well thought out and can be different from what we would typically make after a well-rested night. There is also less capacity for recalling and retaining memories. During REM sleep, your brain organises all you've learnt over the day and sorts it into your memory. When you go through fewer REM cycles of a night, there is less time to organise everything, and information can be partially lost (B. Rasch and J. Born, 2013)
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Does lack of sleep have long term effects?
editConsistently not getting enough sleep can have various health impacts on the body including increased risk of cardiovascular diseases, increases blood pressure, increased risk of developing diabetes and obesity. It can also have negative impacts on the brain as low sleep can lead to depression and anxiety and has been linked to the onset of various neurodegenerative diseases.
Mental illness
editThe links between sleep and mental health is a widely researched area of psychology. It has been clearly established that a lack of sleep is a common comorbidity in a number of psychiatric disorders, particularly mood disorders, such as schizophrenia and bipolar disorder. Additionally, disruptions in sleep and circadian biology impacts the neural and endocrine functions of individuals which can contribute to atypical patterns of social behaviour and abnormal light exposure.
In schizophrenia, a common feature of the disorder is having sleep disturbances which include reductions in total sleep time, poor sleeping efficiency, increased sleep latency and reduced REM sleep, with 30-80% of all schizophrenic patients reportedly having poor sleep (Cohrs, 2008). In children, it has been reported that prodromal sleep disturbances are a common feature of early-onset schizophrenia (Mattai et al, 2006). From a biological perspective, poor sleep affects schizophrenic patients through compromising their circadian biology and resulting in fragmenting and instability in their rest-activity cycles.
In both Bipolar I and II, having poor sleep is a good predictor of the likelihood of someone developing the condition. This is because people with Bipolar disorder tend to struggle falling asleep, have a lower requirement for sleep and their sleep is easily disturbed.
Increased risk of neurodegenerative diseases
editWhen you sleep for less then 7 hours a night the proteins in your brain called beta-amyloid build up, and an excess of it can lead to Alzheimers Disease (AD). Your brain has a build up of beta-amyloid during the day, the exact function is still unclear, and is degraded my microglia as we sleep.
A disturbance in sleep patterns is one of the first symptoms of AD, 25-60% of people with the diease suffer from various sleep disorders (Vaou et al., 2018). Melatonin production decreases as we age and even more so in AD patients. This has been hypothesised to contribute to the phenomenon known as "Sun-downing" in which a person with AD becomes anxious, irritable and disoriented during the dusk as the sun begins to set (Liu et al., 1999; Sanders etal., 2012).
How does sleep affect performance?
editA lack of self-control can lead to poor decisions and interactions both in your personal and professional life. With less self-control your ability to regulate facial expressions, tone and choice of words is all impaired which can lead to conflict. It also leaves you less aware of your surroundings and can lead to increased risk of injury both in the workplace and in sports.
Work
editIt is important to come to work well rested for both yourself and the people around you. Little or poor sleep has shown to increase unsafe and unethical practises within the workforce (Barns et al., 2011). It also makes it harder to maintain interpersonal relationships, especially if irritability caused by a lack of sleep occurs for weeks on end. No-body wants to be friends with a grouch.
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Case study:  In a study by Mei Chen et al. (2022), 79 employees were sampled across the East Coast of China to test hypotheses surrounding sleep and ego depletion and whether or not these affected workplace conflict. The study found that those with less sleep or a poor quality of sleep experience more conflict in the workplace. It was suggested that the cause of this was ego depletion when an individual did not get enough sleep and hence had less self-control than usual, causing more conflicts. The study also stressed the importance of sleep in avoiding burnout and consequently leaving the workplace. Figure 2 is an older example of this. Ultimately, it emphasised that allowing workers to get enough sleep would improve workplace morale and productivity by avoiding ego depletion. |
Athletes
editIn professional sports, athletes are more likely to have a more disrupted sleep which increases the risk of injury (Huang and Ihm, 2021). Athletes who get less than 7 hours of sleep per night are 1.7 times more likely to get injured than those who recieve a full 8 hours (Milewski et al., 2014). This is due to the impaired decision-making, while there may be less overt decisions being made during training, there are lots of micro decisions being made, "where should I step", and some decisions such as "do i need to stop pushing" can fall to the way side when there is less capacity for a well rounded perspective thus increasing the chance of injury. Getting a good nights sleep has been shown to increase the rate of recovery for certain injuries as the body has time to repair during sleep. (Vermier et al., 2021)
Conclusion
editDecision making and willpower is closely linked to how much quality sleep we get per night. When we get less than 7 our brains are unable to sort through the information we received the day before and there is less energy available for making decisions. Sleep is an important part of our days as it clears toxins from our brains and creates new neural networks based on our experiences from the day before. Consistently not sleeping can lead to serious health impacts and increase our risk of mental health issues and developing neurodegenerative diseases such as AD. It also effects out work lives because when we lack self-control there is a negative impact on those around us and out interpersonal relationships are impacted and you are more likely to make mistakes that lead to injury. When life gets crazy and it feels like there are less hours in the day to accomplish all you need to, remember to prioritise sleep as it will give you the much needed. energy to successfully function throughout the day.
See also
edit- Ego Depletion (Wikipedia)
- Sleep deprivation (Wikipedia)
References
editChen, M., Dong, H., Luo, Y., & Meng, H. (2022). The Effect of Sleep on Workplace Interpersonal Conflict: The Mediating Role of Ego Depletion. International Journal of Mental Health Promotion, 24(6), 901-916. https://doi.org/https://doi.org/10.32604/ijmhp.2022.020006
Cohrs, S. (2008) Sleep disturbances in patients with schizophrenia: Impact and effect of antipsychotics. CNS Drugs, 22(11), 939-962. https://doi.org/10.2165/00023210-200822110-00004
Foster, R.G., Peirson, S., Wulff, K., Winnebeck, E., Vetter, C., Roenneberg, T. (2013) Sleep and circadian rhythm disruption in social jetlag and mental illness. Progress in Molecular Biology and Translational Science, 119, 325-346. https://dx.doi.org/10.1016/B978-0-12-396971-2.00011-7
Homberg, J. R. (2012). Serotonin and decision making processes. Neuroscience & Biobehavioral Reviews, 36(1), 218-236. https://doi.org/https://doi.org/10.1016/j.neubiorev.2011.06.001
Huang, K., & Ihm, J. (2021). Sleep and Injury Risk. Current Sports Medicine Reports, 20(6), 286-290. https://doi.org/10.1249/jsr.0000000000000849
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Liu, R. Y., Zhou, J. N., van Heerikhuize, J., Hofman, M. A., & Swaab, D. F. (1999). Decreased melatonin levels in postmortem cerebrospinal fluid in relation to aging, Alzheimer's disease, and apolipoprotein E-epsilon4/4 genotype. J Clin Endocrinol Metab, 84(1), 323-327. https://doi.org/10.1210/jcem.84.1.5394
Matthew T. Gailliot, R. F. B., C. Nathan DeWall, Jon K. Maner, E. Ashby Plant, Dianne M. Tice, and Lauren E. Brewer. (2007). Self-Control Relies on Glucose as a Limited Energy Source: Willpower Is More Than a Metaphor. Journal of Personality and Social Psychology, 92(2), 325-336. https://doi.org/10.1037/0022-3514.92.2.325
Mattai, A.A., Tossell, J., Greenstein, D.K., et al. (2006) Sleep disturbances in childhood-onset schiozophrenia. Schizophr Res. 86(1-3), 123-129. https://doi.org/10.1016/j.schres.2006.04.020
Molden, D. C., Hui, C. M., Scholer, A. A., Meier, B. P., Noreen, E. E., D’Agostino, P. R., & Martin, V. (2012). Motivational Versus Metabolic Effects of Carbohydrates on Self-Control. Psychological Science, 23(10), 1137-1144. https://doi.org/10.1177/0956797612439069
Milewski, M. D., Skaggs, D. L., Bishop, G. A., Pace, J. L., Ibrahim, D. A., Wren, T. A. L., & Barzdukas, A. (2014). Chronic Lack of Sleep is Associated With Increased Sports Injuries in Adolescent Athletes. Journal of Pediatric Orthopaedics, 34(2), 129-133. https://doi.org/10.1097/bpo.0000000000000151
Monti, J. M. (2011). Serotonin control of sleep-wake behavior. Sleep Medicine Reviews, 15(4), 269-281. https://doi.org/https://doi.org/10.1016/j.smrv.2010.11.003
Murphy, E. R., Fernando, A. B., Urcelay, G. P., Robinson, E. S., Mar, A. C., Theobald, D. E., Dalley, J. W., & Robbins, T. W. (2012). Impulsive behaviour induced by both NMDA receptor antagonism and GABAA receptor activation in rat ventromedial prefrontal cortex. Psychopharmacology (Berl), 219(2), 401-410. https://doi.org/10.1007/s00213-011-2572-1
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Pacheco, D. (2020, December 4). Sleep & Glucose: How Blood Sugar Can Affect Rest. Sleep Foundation. https://www.sleepfoundation.org/physical-health/sleep-and-blood-glucose-levels
Paine, T. A., Slipp, L. E., & Carlezon, W. A., Jr. (2011). Schizophrenia-like attentional deficits following blockade of prefrontal cortex GABAA receptors. Neuropsychopharmacology, 36(8), 1703-1713. https://doi.org/10.1038/npp.2011.51
Pilat, D., & Sekoul, K. (2021). Ego Depletion. The Decision Lab. https://thedecisionlab.com/reference-guide/psychology/ego-depletion
Pilcher, J. J., Morris, D. M., Donnelly, J., & Feigl, H. B. (2015). Interactions between sleep habits and self-control. Front Hum Neurosci, 9, 284. https://doi.org/10.3389/fnhum.2015.00284
Porter, V. R., Buxton, W. G., & Avidan, A. Y. (2015). Sleep, Cognition and Dementia. Current Psychiatry Reports, 17(12), 97. https://doi.org/10.1007/s11920-015-0631-8
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Sanders, M. A., Shirk, S. D., Burgin, C. J., & Martin, L. L. (2012). The Gargle Effect:Rinsing the Mouth With Glucose Enhances Self-Control. Psychological Science, 23(12), 1470-1472. https://doi.org/10.1177/0956797612450034
Schür, R. R., Draisma, L. W., Wijnen, J. P., Boks, M. P., Koevoets, M. G., Joëls, M., Klomp, D. W., Kahn, R. S., & Vinkers, C. H. (2016). Brain GABA levels across psychiatric disorders: A systematic literature review and meta-analysis of (1) H-MRS studies. Hum Brain Mapp, 37(9), 3337-3352. https://doi.org/10.1002/hbm.23244
Siegel, J. M. (2004). The neurotransmitters of sleep. J Clin Psychiatry, 65 Suppl 16(Suppl 16), 4-7.
Thakkar, M. M. (2011). Histamine in the regulation of wakefulness. Sleep Medicine Reviews, 15(1), 65-74. https://doi.org/https://doi.org/10.1016/j.smrv.2010.06.004
Torrealba, F., Riveros, M. E., Contreras, M., & Valdes, J. L. (2012). Histamine and motivation. Front Syst Neurosci, 6, 51. https://doi.org/10.3389/fnsys.2012.00051
Vaou, O. E., Lin, S. H., Branson, C., & Auerbach, S. (2018). Sleep and Dementia. Current Sleep Medicine Reports, 4(2), 134-142. https://doi.org/10.1007/s40675-018-0112-9
Vermeir, P., Leye, M. D., Grymonprez, R., Goethals, A., Vermeir, R., Bossche, L. V., & Mariman, A. (2021). 456 The impact of sleep on the recovery of sport injuries. British Journal of Sports Medicine, 55(Suppl 1), A173-A174. https://doi.org/10.1136/bjsports-2021-IOC.417
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Zaffanello, M., Pietrobelli, A., Cavarzere, P., Guzzo, A., & Antoniazzi, F. (2024). Complex relationship between growth hormone and sleep in children: insights, discrepancies, and implications [Review]. Frontiers in Endocrinology, 14. https://doi.org/10.3389/fendo.2023.1332114
External links
edit- Brain Basics: Understanding Sleep (https://www.ninds.nih.gov/health-information/public-education/brain-basics/brain-basics-understanding-sleep)
- Sleep (Cleveland Clinic)