Hypersomnia: what is excessive sleepiness and can it be treated?

Written by: Professor Matthew Walker
Edited by: Bronwen Griffiths

Hypersomnia is a sleep condition characterised by daytime or excessive sleepiness. It can vary in intensity and can have different causes. Professor Matthew Walker, a top neurologist, explains what hypersomnia is, its causes and the unfortunate effects this problem can have on people’s lives.

What is hypersomnia?

Hypersomnia is excessive sleepiness and it happens in different forms, so some people may be sleepy throughout the day, or they may become very sleepy at certain points during the day. Other people may have sleep attacks where they may be usually well between these attacks but get sudden overwhelming sleepiness, often in socially awkward or inconvenient circumstances, such as during a meal or evening conversations with people.

When people actually have hypersomnia, they will often doze or fall asleep. They may sleep for anything, from a few minutes, seconds, and sometimes up to hours, depending on the cause of their hypersomnia.

The other form of hypersomnia that we often see is where people will have ‘micro’ sleeps during the day in which they may carry out strange, automatic actions such as sticking their socks in the fridge or writing nonsense without actually being aware of what they are doing because their brain is partially asleep.

What are the causes of hypersomnia?

The commonest cause of hypersomnia is getting inadequate amounts of sleep at night. We all need different lengths of sleep, and some people will restrict their sleep unnecessarily, leading them to be sleepy during the day. The other commonest cause of excessive sleepiness during the day is not getting adequate sleep at night because sleep is disturbed. There may be a range of conditions that do that.

The branch of hypersomnia that interests me most is narcolepsy. Narcolepsy is a very specific condition in which hypersomnia is caused by dysregulation of sleep so that people will get sleep attacks during the day but also have disturbed and disrupted sleep at night. The understanding of what causes that is something that I find particularly fascinating.

More recently, it has been discovered that there are brain cells that specifically regulate our sleep and it may be damage to those brain cells that cause the condition. Therefore, because of that and because those brain cells never grow again, narcolepsy is a condition that is lifelong. Hence, it can have a devastating effect on people’s lives if left untreated.

What effects can hypersomnia have?

Hypersomnia can have a devastating effect on people’s lives. Being excessively sleepy means that people cannot drive. It also may affect their work because they may be falling asleep at work. It can also affect everyday aspects of life, for example, personal relationships or the ability to do things around the house. Hypersomnia affects all aspects of a person’s life.

It is not uncommon for people with hypersomnia to feel down or to become depressed. As a result of their inability to do things and to socialise, patients can become socially isolated.

Lastly, sleep has a very critical role in memory, memory formation and concentration. Therefore, those who suffer from hypersomnia can have problems with memory and concentration.

How can hypersomnia be treated?

The most important thing in treating hypersomnia is making an accurate diagnosis. If the patient is not getting an adequate amount of sleep, then treatment would look to increase the amount of sleep they are getting. If their sleep is disturbed, then treating what is disturbing their sleep is a priority.

We all have a clock in our brain that tells us when we should go to sleep, when we should get up and when we should eat. An important thing about this is that the brain likes to have a routine; a regular bedtime and a regular wake-up time. If we tend to disturb that routine or sleep for irregular hours, then that can disrupt and disturb our sleep overnight. If we get an inadequate amount of sleep during the week, we will try to catch up on the weekend by lying in, which unfortunately is not a good habit for our body clock.

For patients whose hypersomnia is due to narcolepsy, treatment is a bigger challenge. This is because they will need stimulants during the day to try to keep them awake. Interestingly, because people with narcolepsy have dysregulated sleep, sometimes giving them something to help them sleep at night may improve their sleepiness during the day. It is often a combination of using something at night to help them sleep and something during the day to keep them awake.

By Professor Matthew Walker

Professor Matthew Walker is a top neurological clinician and expert in the field of epilepsy and neurological sleep disorders. A Cambridge graduate, he treats these disorders from his Queen's Square London clinic. He is a pioneer in his research field and has published 100s of articles, book chapters, and books.

In addition, he is head of the Department of Clinical and Experimental Epilepsy at University College London, and the National Hospital for Neurology and Neurosurgery, and also serves as a council member of national and international epilepsy boards and associations. He received the Ambassador for Epilepsy award from the International League Against Epilepsy in 2013.

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