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An approach to excessive daytime sleepiness in adults

BMJ 2020; 368 doi: (Published 27 March 2020) Cite this as: BMJ 2020;368:m1047
  1. James Brown, consultant respiratory physician1,
  2. Himender K Makker, consultant physician in respiratory and sleep medicine2
  1. 1Royal Free Hospital, London, UK
  2. 2Department of Thoracic Medicine, University College London Hospital, London, UK
  1. Correspondence to HK Makker himender.makker{at}

What you need to know

  • Differentiating excessive daytime sleepiness (EDS) from symptoms of fatigue or being “tired all the time” is key to accurate diagnosis

  • The Epworth Sleepiness Scale (ESS) score is a useful way to assess and classify EDS. An ESS >10 indicates EDS and >17 indicates severe EDS

  • Obstructive sleep apnoea, periodic limb movement syndrome, narcolepsy, and circadian rhythms are some of the commonest causes of EDS

  • Treating obstructive sleep apnoea reduces excessive daytime sleepiness, improves neuropsychological function, and reduces blood pressure

  • Refer patients with EDS for assessment, including overnight sleep study

Excessive daytime sleepiness (EDS) is best described as an urge to sleep during daytime hours. It is a common problem, occurring at least three days a week in 4-20% of the population,1 and affects quality of life, workplace performance, and has safety implications, for example, when driving. Sleep disorders that cause excessive daytime sleepiness remain underdiagnosed and are easy to miss in clinical practice.2 Insomnia is a common cause of daytime sleepiness, but other disorders are important to consider. This review discusses the different potential causes of excessive daytime sleepiness in adults and proposes an approach to management and referral in non-specialist settings, in particular how to identify disorders that require referral to secondary care.

What is excessive daytime sleepiness and how is it different from fatigue?

It is important to distinguish EDS from fatigue. EDS is defined as the inability to maintain wakefulness and alertness during the major waking episodes of the day, with sleep occurring unintentionally or at inappropriate times almost daily for at least three months.3 It is used interchangeably with hypersomnia and hypersomnolence, although according to ICD-4, hypersomnolence is excessive sleepiness when wakefulness is expected, and hypersomnia is a disorder characterised by hypersomnolence.

Patients may report sleepiness as a vague symptom of fatigue or feeling “tired all the time.” When assessing a patient, it is useful …

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