Tiredness (also known as fatigue) is an extremely common problem. In fact, “why am I so tired?” was one of the most frequently searched questions of the last 2 years at Google. The answers can vary, since tiredness can come from a physiological or psychological condition. In this article we’ll discuss 10 of the main causes of fatigue.   


Anemia is a condition characterized by a low number or abnormal shape of red blood cells. In some countries up to 10% of the population is at risk of developing some kind of anemia, mostly due to low levels of iron. Pregnant women are especially vulnerable to it. There are several types of anemia; however, the one caused by iron deficiency is the most commonly related to fatigue.

Iron deficiency is related to fatigue mainly because this ion is essential for oxygen transportation, ATP production (the main energy currency of the cell) and muscle function. People with this condition usually experience dizziness and get tired easily.


This condition involves blocking of the upper airways during sleep which leads to short periods where the person is not able to breathe. This can be caused by a number of factors like obesity, genetic disorders, kidney failure, etc.   

The lack of sleep and sudden shortage of oxygen eventually lead to general sleepiness and fatigue in most cases. So far, women have proved to be more vulnerable to this condition.


The condition is also known as Hypothyroidism. It is characterized by a low production of important hormones. Since early symptoms are very common for many other diseases, people can spend many years without being diagnosed.

Usually, the symptoms include weight gain, depression, muscle ache, sensitivity to cold, dry skin and hair and of course, fatigue.

This condition can be treated with hormone therapy.


Also known as infectious mononucleosis, this infection is mostly seen in adolescents or adults who haven’t been infected with the Epstein-Barr virus before, people can be infected and show no symptoms for nearly 2 months. 

Although fever is the main symptom, fatigue is the one that lasts the longest (up to 6 months after the infection).


Depression is the term usually used when someone feels sad or anxious for an extended period of time. People that have been depressed for a long period of time (over 2 years) can develop feelings of tiredness as part of a particular form of depression called dysthymia.

However, in literature, is common to see depression as the consequence of chronic fatigue syndrome. People who live with the syndrome often spend very long periods of their lives without effective treatment of diagnosis, which leads to feelings of hopelessness and eventually depression.

There are plenty of other reasons for why you may feel tired all the time, for example, if you are fighting an infection, it often triggers what some call “sickness behavior”, which sometimes includes fatigue. Overall, any condition related to chronic inflammation has the potential to cause tiredness. Or it simply could be that you need to make dietary changes. Whatever the case, if you If you experience long periods of fatigue and are concerned, talk to your doctor.  

Hector Osorio 29 Jan 2019