Excessive daytime sleepiness can occur for different reasons. For many people, feelings of tiredness can be attributed to not getting enough sleep at night, but several sleep disorders Trusted Source American Academy of Sleep Medicine (AASM) AASM sets standards and promotes excellence in sleep medicine health care, education, and research. View Source can also cause daytime sleepiness.

Sleep deficiency and daytime sleepiness may lead to negative outcomes Trusted Source National Heart, Lung, and Blood Institute (NHLBI) The NHLBI is the nation's leader in the prevention and treatment of heart, lung, blood and sleep disorders. View Source at work or school. People who feel sleepy during the day and awake at night may struggle with focusing and concentrating at work, and tiredness can also impact decision-making and emotional control. Another concern is an increased risk of being involved in an accident on the road. Thankfully, there are measures you can take to mitigate daytime sleepiness and get enough sleep each night.

Why Does Daytime Tiredness Occur?

Daytime tiredness is different from fatigue. Fatigue refers to a lack of energy motivation Trusted Source Medline Plus MedlinePlus is an online health information resource for patients and their families and friends. View Source that may occur due to lack of sleep, but can also stem from other factors like emotional stress or boredom.

Certain sleep disorders can lead to feelings of excessive daytime sleepiness. These include:

  • Sleep apnea: This disorder is characterized by a restriction or blockage to the upper airway that causes people to choke or gasp for air in their sleep, often waking up in the process. Sleep apnea can also cause heavy snoring that disrupts sleep and makes people – and their partners – feel tired the next day.
  • Narcolepsy: Narcolepsy is defined as the overwhelming urge to sleep during the day, which in turn can interfere with nightly sleep. During “sleep attacks,” some people with narcolepsy experience cataplexy, or the sudden loss of muscle tone that causes them to fall or slump over as they nod off. Excessive daytime sleepiness is considered the chief symptom of narcolepsy.
  • Hypersomnia: Hypersomnia is another condition that causes people to feel excessively tired during the day. Unlike narcolepsy, hypersomnia does not cause sleep attacks Trusted Source Medline Plus MedlinePlus is an online health information resource for patients and their families and friends. View Source and cataplexy will not occur. Many people with this condition have idiopathic hypersomnia, meaning the cause is not known.
  • Delayed sleep-wake phase disorder: People with this disorder – DSWPD for short – feel tired later in the evening compared to other people, and they may also wake up later as a result. It occurs when a person’s circadian rhythm, guiding their sleep-wake schedule, is not aligned with natural light and darkness cycles. Those who attempt to correct their delayed sleep-wake phase may experience excessive sleepiness the next day.
  • Non-24-hour sleep-wake rhythm disorder: The circadian rhythms of most healthy adults will reset every 24 hours in order to align with daylight and darkness. For people with this disorder, circadian rhythms are not entrained in a 24-hour schedule. Excessive daytime sleepiness is considered a chief symptom of non-24-hour sleep-wake rhythm disorder.
  • Shift work disorder: Another circadian rhythm condition, shift work disorder affects people whose jobs require them to work late at night or early in the morning, and sleep during the day. The disorder can cause excessive daytime or nighttime sleepiness, depending on when the person works, and also cause sleep disruptions during their allotted rest time.

Another disorder, “insufficient sleep syndrome,” occurs when people persistently fail to get enough sleep at night due to factors such as family responsibilities or a work schedule that requires early rising. Tiredness during the day often occurs as a result. Interestingly, the most commonly diagnosed sleep disorder – insomnia – does not necessarily cause excessive daytime sleepiness. People with insomnia usually experience fatigue Trusted Source National Center for Biotechnology Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source from being unable to sleep, rather than feelings of excessive tiredness that compel them to sleep. Apart from sleep disorders, other factors can cause excessive tiredness during the day. Jet lag, a circadian rhythm condition that affects overseas travelers adjusting to their current time zone, can make people very tired during the day. Sedative medications are also known to cause daytime tiredness. Additionally, one 2019 study suggests excessive sleepiness may be genetically inherited Trusted Source National Library of Medicine, Biotech Information The National Center for Biotechnology Information advances science and health by providing access to biomedical and genomic information. View Source .


How Much Sleep Do You Need?

Adults generally need seven to eight hours of sleep each night. According to a survey conducted by the Centers for Disease Control and Prevention, nearly 35% of respondents Trusted Source Centers for Disease Control and Prevention (CDC) As the nation’s health protection agency, CDC saves lives and protects people from health threats. View Source reported getting six or fewer hours of nightly sleep. Since a good night’s rest is essential for bodily recovery and repair, those who don’t get enough sleep on a regular basis are at higher risk for certain disorders Trusted Source National Institute of Neurological Disorders and Stroke (NINDS) NINDS aims to seek fundamental knowledge about the brain and nervous system and to use that knowledge to reduce the burden of neurological disease. View Source , including high blood pressure, cardiovascular disease, obesity, diabetes, and depression.

As you can see from our recommendations, the amount of sleep you should get each night will evolve over the course of your life.

Age GroupAge RangeRecommended Amount of Sleep per Day
Newborn0-3 months14-17 hours
Infant4-11 months12-15 hours
Toddler1-2 years11-14 hours
Preschool3-5 years10-13 hours
School-age6-13 years9-11 hours
Teen14-17 years8-10 hours
Young Adult18-25 years7-9 hours
Adult26-64 years7-9 hours
Older Adult65 years or older7-8 hours

If you feel tired during the day after a night without enough sleep, you may be able to alleviate your tiredness by simply getting more rest. Another remedy may be improving your sleep hygiene by going to bed and waking up at the same times each day, avoiding caffeine in the afternoon and evenings, and maintaining a relaxing bedroom environment.

However, persistent feelings of excessive daytime tiredness may warrant a doctor’s visit – especially if you sleep for the recommended amount of time each night.

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9 Sources

  1. American Academy of Sleep Medicine. (2014). The International Classification of Sleep Disorders – Third Edition (ICSD-3). Darien, IL

  2. National Heart, Lung, and Blood Institute. (n.d.). Sleep deprivation and deficiency., Retrieved October 30, 2020, from

  3. U.S. National Library of Medicine. (2020, October 8). Fatigue. MedlinePlus., Retrieved October 30, 2020, from

  4. A.D.A.M. Medical Encyclopedia. (2019, April 8). Idiopathic hypersomnia. MedlinePlus., Retrieved October 30, 2020, from

  5. Singareddy, R., Bixler, E. O., & Vgontzas, A. N. (2010). Fatigue or Daytime Sleepiness? Journal of Clinical Sleep Medicine, 6(4), 405., Retrieved from

  6. Pagel, J.F., Pandi-Perumal, S.R. & Monti, J.M. Treating insomnia with medications. Sleep Science Practice 2, 5 (2018)., Retrieved from

  7. Wang, H., Lane, J.M., Jones, S.E. et al. Genome-wide association analysis of self-reported daytime sleepiness identifies 42 loci that suggest biological subtypes. Nat Commun 10, 3503 (2019)., Retrieved from

  8. Liu Y, Wheaton AG, Chapman DP, Cunningham TJ, Lu H, Croft JB. Prevalence of Healthy Sleep Duration among Adults — United States, 2014. MMWR Morb Mortal Wkly Rep 2016;65:137–141. DOI:

  9. National Institute of Neurological Disorders and Stroke. (2019, August 23). Brain basics: Understanding sleep.


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