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Top Causes of Fatigue and Sleepiness

We all tend to feel tired, exhausted, and unnaturally sleepy every now and then. And neither are you alone in feeling exhausted and having little energy. There can be many reasons why you are feeling tired and sleepy. It could be due to simple causes like lack of sleep or coming down with an infection, or the flu. Or it could also be due to an underlying medical condition. Even though it is normal to experience fatigue and sleepiness every now and then, but chronic fatigue and sleepiness can have an impact on the quality of your life, preventing you from doing many of the things you enjoy. Let us look at some of the top causes of fatigue and sleepiness.

Top Causes of Fatigue and Sleepiness

Top Causes of Fatigue and Sleepiness

  1. Not Getting Good Quality Of Sleep

    It is not only essential to get at least six to seven hours of sleep every night but also to get enough good quality sleep. What is unfortunate is that most of us do not get enough high-quality sleep, which leads to fatigue and sleepiness.

    When we sleep, the body performs a large number of critical processes. This includes the release of many important growth hormones, giving rest to the muscles, repairing and regenerating of cells. This is one of the reasons why most people wake up feeling energized, refreshed, and alert after getting a full night of high-quality sleep.(1, 2)

    Most importantly, when you are sleeping, it should be uninterrupted and restful. Only then will the brain go through the three stages of non-rapid eye movement (NREM) sleep as well as one stage of rapid eye movement sleep (REM), which is the stage of sleep during which you dream.(3)

    According to the American Academy of Sleep Medicine and Sleep Research Society, while sleep time for every person is different, but as a general rule of thumb, adults should be getting at least seven hours of sleep each night for good health.(4) However, the problem is that even though everyone knows the importance of getting sufficient sleep, the problem arises in falling and staying asleep throughout the night.

    Insomnia is a term that is used to refer to any condition that causes you to have trouble falling asleep or remain asleep through the night. There can be many factors responsible for insomnia, including medical conditions, menopause, poor sleeping environment, stress and sometimes even excessive mental stimulation.(5)

    Insomnia has become one of the leading causes of people feeling sleepy and tired during the day today. One review even found that nearly 40 percent of adults in the United States experience insomnia at some point in a year. What is even more common is short-term insomnia, which lasts for less than three months. While it affects 9.5 percent of the population in the US, out of this, one in five cases transforms into chronic insomnia that not only lasts longer than three months but also affects your sleep at least three or more times in a week.(6)

    If you are experiencing sleepiness and fatigue due to insomnia, there are many treatments like medications, natural supplements, and lifestyle changes. Treating the underlying medical cause of insomnia will also help. You should make an appointment with a doctor to get the right treatment and care at the earliest.

  2. Stress

    Even though stress has become a normal part of our daily lives today, it is chronic stress that one should worry about, as that is linked directly to fatigue.(7, 8, 9) Studies have even suggested that chronic stress may cause stress-related exhaustion disorder (ED), which is a medical condition that causes both physical and psychological symptoms of exhaustion.(10)

    In addition to this, chronic stress is also known to cause some functional and structural changes in the brain, leading to chronic inflammation that is known to contribute to symptoms like sleepiness and fatigue.(11)

    While it is not always possible to avoid stress, especially stress stemming from family or work situations, it is still advisable that you try to manage your stress to prevent complete burnout or exhaustion. Meditating, taking a hot bath, reading, or going for a walk may help you decompress.(12)

  3. Deficiencies in Certain Nutrients

    Nutrient deficiencies are also known to make a person feel sleepy and tired on a daily basis. This can be true even after getting seven or more hours of sleep. Deficiency in the following nutrients is primarily known to make you feel sleepy and tired:(13, 14)

    It is pretty common to see deficiencies in these nutrients, with iron deficiency being the most common type, often known to cause anemia. Nearly 25 percent of the world’s population is affected by anemia, and 50 percent of anemia is known to be caused by iron deficiency. Fatigue and sleepiness are the most common symptoms of anemia, and it improves once the iron levels are restored.(15)

    Studies have shown that nearly 20 percent of people in the UK and US who are aged 60 and above suffer from vitamin B12 deficiency. This deficiency is especially common in the elderly since, with age, the body’s ability to absorb vitamin B12 starts to decline.(16) This vitamin is essential for energy production and oxygen delivery, which is why you may feel extremely fatigued due to low levels of vitamin B12.

    Deficiency of vitamin D may also cause sleepiness and fatigue. It is estimated that over half the world’s population suffers from a shortage of vitamin D.(17)

    Since deficiencies of these nutrients are fairly common, you should consider getting your levels tested from time to time, especially if you are experiencing unexplained sleepiness and fatigue. Usually, fatigue and drowsiness related to these deficiencies will improve once the nutrient levels get back to normal.


Even though we all have days when we feel tired and sleepy, perpetually feeling sleepy and fatigued is not normal. There can be many possible causes behind chronic fatigue and drowsiness, such as nutrient deficiencies, chronic stress, and lack of good sleep. If you are experiencing unexplained tiredness and drowsiness, it is essential to discuss it with your doctor so that the underlying cause can be determined. In most cases, fatigue and sleepiness should improve once the underlying cause has been determined and treatment or adjustments started.


  1. Brinkman, J.E., Reddy, V. and Sharma, S., 2018. Physiology of sleep.
  2. Chaput, J.P., Dutil, C. and Sampasa-Kanyinga, H., 2018. Sleeping hours: what is the ideal number and how does age impact this?. Nature and science of sleep, 10, p.421.
  3. Consensus Conference Panel, Watson, N.F., Badr, M.S., Belenky, G., Bliwise, D.L., Buxton, O.M., Buysse, D., Dinges, D.F., Gangwisch, J., Grandner, M.A. and Kushida, C., 2015.
  4. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Journal of Clinical Sleep Medicine, 11(6), pp.591-592.
  5. Anon, 2022. American Academy of Sleep Medicine (AASM): Sleep: Medical society. American Academy of Sleep Medicine – Association for Sleep Clinicians and Researchers. Available at: https://aasm.org/ [Accessed August 28, 2022].
  6. Proserpio, P., Marra, S., Campana, C., Agostoni, E.C., Palagini, L., Nobili, L. and Nappi, R.E., 2020. Insomnia and menopause: a narrative review on mechanisms and treatments. Climacteric, 23(6), pp.539-549.
  7. Dopheide, J.A., 2020. Insomnia overview: epidemiology, pathophysiology, diagnosis and monitoring, and nonpharmacologic therapy. The American journal of managed care, 26(4 Suppl), pp.S76-S84.
  8. Doerr, J.M., Ditzen, B., Strahler, J., Linnemann, A., Ziemek, J., Skoluda, N., Hoppmann, C.A. and Nater, U.M., 2015. Reciprocal relationship between acute stress and acute fatigue in everyday life in a sample of university students. Biological psychology, 110, pp.42-49.
  9. Rose, D.M., Seidler, A., Nübling, M., Latza, U., Brähler, E., Klein, E.M., Wiltink, J., Michal, M., Nickels, S., Wild, P.S. and König, J., 2017. Associations of fatigue to work-related stress, mental and physical health in an employed community sample. BMC psychiatry, 17(1), pp.1-8.
  10. Wallensten, J., Åsberg, M., Nygren, Å., Szulkin, R., Wallén, H., Mobarrez, F. and Nager, A., 2016. Possible biomarkers of chronic stress induced exhaustion-a longitudinal study. Plos one, 11(5), p.e0153924.
  11. Gavelin, H.M., Neely, A.S., Dunås, T., Eskilsson, T., Järvholm, L.S. and Boraxbekk, C.J., 2020. Mental fatigue in stress-related exhaustion disorder: Structural brain correlates, clinical characteristics and relations with cognitive functioning. NeuroImage: Clinical, 27, p.102337.
  12. Mariotti, A., 2015. The effects of chronic stress on health: new insights into the molecular mechanisms of brain–body communication. Future science OA, 1(3).
  13. Behan, C., 2020. The benefits of meditation and mindfulness practices during times of crisis such as COVID-19. Irish journal of psychological medicine, 37(4), pp.256-258.
  14. Tardy, A.L., Pouteau, E., Marquez, D., Yilmaz, C. and Scholey, A., 2020. Vitamins and minerals for energy, fatigue and cognition: a narrative review of the biochemical and clinical evidence. Nutrients, 12(1), p.228.
  15. Nowak, A., Boesch, L., Andres, E., Battegay, E., Hornemann, T., Schmid, C., Bischoff-Ferrari, H.A., Suter, P.M. and Krayenbuehl, P.A., 2016. Effect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trial. Medicine, 95(52).
  16. Warner, M.J. and Kamran, M.T., 2017. Iron deficiency anemia.
  17. Gana, W., De Luca, A., Debacq, C., Poitau, F., Poupin, P., Aidoud, A. and Fougère, B., 2021. Analysis of the Impact of Selected Vitamins Deficiencies on the Risk of Disability in Older People. Nutrients, 13(9), p.3163.
  18. Sizar, O., Khare, S., Goyal, A., Bansal, P. and Givler, A., 2021. Vitamin D deficiency. In StatPearls [Internet]. StatPearls Publishing.
Team PainAssist
Team PainAssist
Written, Edited or Reviewed By: Team PainAssist, Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:September 23, 2022

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