Sleep Deprived: Why and How Fatigue negatively impacts the brain

Written By: McKenzie McFall 

Edited By: Keoni Andrews

Everyone on the planet needs to sleep. Outside of food and water, sleep is one of the most important things humans do to make sure we do not get exhausted and have enough energy to complete  daily activities. Sleep is an incredibly important matter to humans. It is recommended that humans get at least 8 hours of sleep per night in order to do their daily functions, like work, school, hobbies, etc. But other times, some humans get less sleep for an extended amount of time, leading to drowsiness, exhaustion, and increased fatigue.

  Although fatigue is very common,  it is a constant state of being extremely tired.  Waking up becomes difficult  and doing the activities you want to do, when you have the overwhelming urge to sleep. Some of the most common symptoms of fatigue are lack of motivation, having trouble concentrating, increased feelings of irritability, depressive feelings, weakened muscles and joints (Cleveland Clinic, 2023). 

Fatigue not only can mentally impact you, but physically impact you too. Fatigue impacts people because some individuals work in settings, where they might have to work over twelve hour periods or work at unusual times (i.e nightshift jobs). Fatigue is the body’s signal for when someone either needs to take a break or a nap. When sleep is delayed or not given at all, it affects the body’s circadian rhythm. Circadian rhythm is your body’s sleep and wake cycle, which signals the body when it is time to sleep. When the body disrupts its circadian rhythm,  stress levels and fatigue increases,  along with decreased concentration. Worker’s fatigue is a specific type of fatigue, which pertains to workers who work longer hours and get less consistent sleep. Worker’s fatigue increases the risk of accidents and injuries by 18% during evening shifts and 30% during night shifts in comparison to day shifts. (OSHA). 

Neuromuscular fatigue involves physiological processes that occur in structures, like motor cortex or muscle contractile proteins. Motor units in the body are one of the basic elements in the CNS (Central Nervous System) and muscles produce movement in the body. It comprises motor neurons in the ventral horn of the spinal cord, axons, and muscle fibers innervated by the axons. The CNS controls muscle force by modifying the activity of motor units in the muscle. Central and peripheral mechanisms of fatigue have been examined during isolated muscle contractions. Including, maximal and submaximal voluntary contractions torques. Even though some central fatigue has been reported to supraspinal mechanisms,  testing of motor neuron excitability during fatiguing contractions shows slower firing rates not solely due to decreased excitatory input (Abd-Elfattah, 2015). 

Neurological fatigue, often referred as central or brain fatigue, is classified as a state of exhaustion originating in the CNS. It is characterized by lack of energy and inability to sustain cognitive effort. Neurological fatigue differs significantly from tiredness because it is persistent that is not relieved by a full night’s sleep. It can severely impact a person’s ability to work, relationships, and perform daily tasks. Neurological fatigue is the brain's failed ability to do an optimal performance. As it can manifest cognitive impairment, including weakened attention span, difficulties with concertation, and memory and executive functioning problems (Science Sights, 2025). 

Neurological fatigue is one of the most common symptoms across psychiatric and chronic conditions. There are multiple casualties to this fatigue subtype, which presents itself in numerous ways (e.g..) Brain-to-muscle fatigue means that the brain struggles to efficiently communicate with the muscles. Metabolic reasons could be at play which means the cells in the human body lack sufficient energy or when nerve signals fail to transmit properly. It results in the body feeling too heavy or weak. Central fatigue originates in changes to the brain itself. It particularly happens when chronic inflammation is present. Immune system activity produces cytokines (inflammatory chemicals) that travel into the brain. It triggers sickness symptoms such as brain fog, exhaustion, and mental withdrawal. In neurological diseases, this response becomes a chronic condition.  

Sometimes there could be a neurotransmitter imbalance. When dopamine and serotonin levels are disrupted, it can result in energy crashes that result in fatigue. Without dopamine, there is no drive to start or sustain an activity and without serotonin, sometimes a small task can feel extremely difficult. Areas of the brain, like the frontal lobe, hypothalamus, and basal ganglia help the body receive and sustain energy. When those areas are affected by neurological disease, the brain can not function properly (Denis, 2025). 

One of the main drives of neurological fatigue is neuroinflammation, which  activates the brain’s immune system in response to injuries or illness. Neuroinflammation activates microglia and astrocytes, which can lead to cellular dysfunction and oxidative stress. The damage causes bioenergetic decline that limits the brain’s energy supply. Reduced energy can impair the brain’s ability to do cognitive processes. Additionally, it involves dysregulation of neurotransmitters. Dopamine pathways in the basal ganglia are implicated, which can lead to a lack of drive and feelings of exhaustion. Since dopamine is involved in reward-seeking behavior and motivation. Altered levels of serotonin that influence arousal and effort perception contribute to subjective overwhelming fatigue (Science Sights, 2025). 

Neurological fatigue can be one of the main debilitating symptoms of any chronic condition. But, there are some ways to manage it. Taking small breaks or breaking down tasks can help with energy conversation and decrease feelings of fatigue. Some diets, stress management, and certain medications can help address inflammation that can worsen immune overactivity that causes more fatigue. Some supplements like Coenzyme 10 help improve cellular energy production and support mitochondrial function. Building consistent sleep routines and rest time help treat sleep disorders and lessen fatigue. 

Fatigue can be challenging to overcome, even if a person gets  sleep consistently. Sometimes individuals can not avoid it because of their occupation or socioeconomic status. But fatigue can help explain certain behaviors of chronic conditions or neurological fatigue. In turn   giving additional insight on what kind of factors cause fatigue and what kind of research can give better insight on to lessen fatigue.

References

Abd-Elfattah, H. M., Abdelazeim, F. H., & Elshennawy, S. (2015). Physical and cognitive consequences of fatigue: A review. Journal of advanced research, 6(3), 351–358. https://doi.org/10.1016/j.jare.2015.01.011 

“Fatigue.” Cleveland Clinic, https://my.clevelandclinic.org/health/symptoms/21206-fatigue. Accessed 24 Aug. 2026.

Long Work Hours, Extended or Irregular Shifts, and Workers Fatigue . Occupational Safety and Health Administration.

“What Causes Neurological Fatigue and How to Manage It.” ScienceInsights, 20 Nov. 2025, https://scienceinsights.org/what-causes-neurological-fatigue-and-how-to-manage-it/. 

Why Fatigue Is So Common in Neurological Conditions. https://www.neurahealth.co/blog/why-fatigue-is-so-common-in-neurological-conditions. Accessed 24 Aug. 2026.