Excessive daytime sleepiness

Also called Hypersomnia, Daytime sleepiness

Falling asleep in the day is a symptom, not a personality. Sleep apnoea is the commonest treatable cause and is massively under-diagnosed.

What it is

Persistent sleepiness during the day, with a tendency to fall asleep in situations where most people would stay awake.

It is distinct from fatigue, which is tiredness without the drive to sleep, and the distinction matters because the causes differ.

**The commonest treatable cause is sleep apnoea**, which is estimated to affect a large number of people in the UK, most of them undiagnosed. It is treatable, treatment transforms daily life, and the main obstacle is that snoring and daytime sleepiness are treated as a joke rather than a symptom.

Other causes include insufficient sleep, which is by far the most common overall; shift work; narcolepsy; restless legs syndrome and periodic limb movements; depression; hypothyroidism; anaemia; chronic kidney disease; Parkinson's disease and dementia; and a long list of medicines including opioids, antihistamines, antipsychotics, some antidepressants and gabapentinoids.

**Driving is the safety issue.** Falling asleep at the wheel causes fatal collisions, and there is a legal duty to inform the DVLA about excessive sleepiness that affects driving. Nobody should drive while sleepy, and this is worth stating plainly.

The Epworth Sleepiness Scale is a simple questionnaire that quantifies it and is worth completing before an appointment.

Signs you might notice

Falling asleep unintentionally: watching television, reading, in meetings, as a passenger, or at the wheel.

Difficulty staying awake in the afternoon.

Waking unrefreshed however long the night.

Poor concentration and memory, irritability.

Snoring, witnessed pauses in breathing, gasping or choking at night, morning headaches and a dry mouth, all suggesting sleep apnoea.

Sudden muscle weakness with emotion, sleep paralysis or vivid hallucinations on falling asleep, suggesting narcolepsy.

**Do not drive while sleepy, and report to the DVLA where required.**

Urgent: sleepiness with confusion, headache, weakness or vomiting, which suggests a neurological or metabolic cause.

Also assess: sudden onset, or sleepiness in an older person that is new, which may indicate infection, medication effects or delirium.

How it can affect day-to-day life

The commonest cause is simply not enough sleep, and the honest first step is counting hours over a fortnight with a sleep diary rather than assuming a medical cause.

Sleep apnoea is transformed by treatment, and getting a referral requires the symptoms to be described plainly: snoring, witnessed pauses, and the Epworth score. Partners are the best witnesses and should come to the appointment.

Medication review is worthwhile and often productive; many sedating drugs are taken out of habit.

Shift workers face a genuine occupational hazard, and the commute home is the most dangerous part of the shift.

For older people, new sleepiness is often the presentation of infection, medication accumulation or delirium, and should be investigated rather than accepted.

The stigma is real: sleepiness is read as laziness, and people are judged at work and at home for a treatable medical problem.

Napping strategically, 20 minutes, early afternoon, helps some people and worsens night sleep in others.

Supporting someone well

Count the hours first with a two-week sleep diary; insufficient sleep is the commonest cause.

Complete an Epworth Sleepiness Scale and take it to the appointment.

Bring the partner, who has seen the snoring and the pauses.

Ask specifically about sleep apnoea and for a sleep study referral.

Ask for a medication review; sedating drugs accumulate.

Check thyroid function, full blood count and kidney function.

**Do not drive while sleepy.** Report to the DVLA where the rules require it.

Get sudden or new sleepiness in an older person investigated rather than accepted.

Ask about narcolepsy if there is muscle weakness with emotion or sleep paralysis.

Where to get help

A GP practice for assessment, blood tests, medication review and referral to a sleep service.

A sleep clinic for sleep studies and treatment.

The DVLA for driving rules; the medical enquiries line advises.

Narcolepsy UK and Sleep Apnoea Trust for the specific conditions.