Fatigue is a term which is used to describe a lack of energy or an overall feeling of tiredness. This is not the same thing when you feel drowsy or sleepy. When we are fatigued, then we do not have energy and motivation. Nearly every single person is overworked or overtired from time to time. These mentioned instances of a temporary fatigue usually have an identifiable cause and a likely remedy. But the unrelenting exhaustion lasts longer. It is more profound and it is not relieved by rest. This is a nearly constant state of weariness which develops over time and it reduces your concentration, motivation and energy. Fatigue impacts your psychological and emotional well – being . Being sleepy can be a symptom of fatigue but these are not the same conditions. Fatigue is a common symptom of many medical conditions and it can range from mild to serious.  Also this can be a result of some lifestyle choices such as poor diet and lack of exercise. [3,4] If your fatigue does not resolve with proper nutrition and rest or if you think that is caused by some underlying mental or physical health condition, then you need to visit your doctor as soon as possible.
Signs and symptoms of fatigue
Fatigue is a symptom of an underlying disease and this is described in many ways from feeling week or being constantly tired or you have lack of energy. Also there may be other associated symptoms which depends on the underlying cause.
- People who suffer from hypothyroidism may also have symptoms of feeling cold, dry skin and brittle hair. 
- People with diabetes may complain of polyuria (which is excess urination), polydypsia (which is excess thirst) or change of vision. 
- People who suffer from heart disease, anemia of lung disease may complain of tiring easily with minimal activity or shortness of breath [7,8]
It is very important to talk with your doctor if you have some of the mentioned symptoms because your doctor will discover the underlying cause for it and it will give you the best treatment for you.
Causes for fatigue
In the most cases, fatigue can be traced to one or more of your routines or habits, particularly when you have lack of exercise. Also this condition is related to depression. Also there are some rare cases in which fatigue is a symptom of some underlying medical condition and it needs medical treatment. Here are the causes that can lead to fatigue:
Conditions: Unrelenting exhaustion can be a sign of a condition or an effect of the therapies or drugs that you have used to treat it, such as
- Toxin ingestion
- Stress 
- Sleep apnea
- Pain that is persistent
- Obesity 
- Sleep disorders such as insomnia
- Multiple sclerosis 
- Seasonal affective disorder
- Liver disease
- Infections such as flu and cold
- Medications and treatments such as chemotherapy, radiation therapy, pain drugs, heart drugs and antidepressants
- IBD (Inflammatory bowel disease)
- Hypothyroidism – underactive thyroid 
- Hyperthyroidism – overactive thyroid 
- Heart disease 
- Meralgia paresthetica
- Diabetes 
- Depression – major depressive disorder
- Acute liver failure
- Chronic kidney disease
- Chronic infection or inflammation
- Kidney disease
- Chronic fatigue syndrome
- Addison’s disease – this is a disease which can affect your hormone levels
- Eating disorders such as anorexia
- Anemia 
- Acute liver failure
- Autoimmune disorders
- Lifestyle factors: When you take an honest inventory of things which may be responsible for the fatigue if often the first step toward relief. Fatigue can be related to:
- Unhealthy eating habits 
- Consuming too much caffeine
- Medications, such as antihistamines, cough medicines, sedatives, antidepressants
- Periods of emotional stress 
- Lack of sleep
- Using street drugs such as cocaine
- Lack of physical activity 
- Jet lag
- Not eating a nutritious diet
- Being overweight or obese 
- Excess physical activity
- Use of alcohol on a regular basis
If you cannot think of anything which may account for your fatigue, then you need to talk with your doctor.
 Lock AM, Bonetti DL, Campbell ADK. The psychological and physiological health effects of fatigue. Occupational Medicine. 2018;68:502–11.
 Kronholm E, Puusniekka R, Jokela J, et al. Trends in self‐reported sleep problems, tiredness and related school performance among Finnish adolescents from 1984 to 2011. Journal of Sleep Research. 2015;24(1):3-10.
 Azzolino D, Arosio B, Marzetti E, et al. Nutritional status as a mediator of fatigue and its underlying mechanisms in older people. Nutrients. 2020;12(2):444.
 University of Georgia. Low-intensity exercise reduces fatigue symptoms by 65 Percent, study finds. Science Daily. 2008. Retrieved from www.sciencedaily.com/releases/2008/02/080228112008.htm
 Fischer S, Markert C, Strahler J, et al. Thyroid functioning and fatigue in women with functional somatic syndromes – Role of early life adversity. Frontiers in Physiology. 2018;9:564.
 Fritschi C, Quinn L. Fatigue in patients with diabetes: A review. Journal of Psychosomatic Research. 2010;69(1):33–41.
 Appels A, Mulder P. Fatigue and heart disease. The association between ‘vital exhaustion’ and past, present and future coronary heart disease. Journal of Psychosomatic Research. 1989;33(6):727-38.
 Prochaska MT, Newcomb R, Block G, et al. Association between anemia and fatigue in hospitalized patients: Does the measure of anemia matter? Journal of Hospital Medicine. 2017;12(11):898–904.
 Lim W, Hong S, Nelesen R, et al. The association of obesity, cytokine levels, and depressive symptoms with diverse measures of fatigue in healthy subjects. Archives of Internal Medicine. 2005;165(8):910-5. doi:10.1001/archinte.165.8.910
 Rudroff T, Kindred JH, Ketelhut NB. Fatigue in multiple sclerosis: Misconceptions and future research directions. Frontiers in Neurology. 2016;7:122.