Consider other causes of sleepiness, it’s not all narcolepsy

There are many causes of sleepiness, and narcolepsy is only one of them. In managing people with sleepiness it is important to think about what might be causing sleepiness, rather that misusing the term narcolepsy for everyone who is sleepy.

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I just wanted to do a brief video to talk about causes of sleepiness. I have been seeing a lot of people recently who come to me with a label of narcolepsy where really their symptoms have been of sleepiness and there’s lots more causes of sleepiness rather than just narcolepsy.

Now, that’s not something that’s not well understood amongst health professionals. Often the term narcolepsy is used to describe sleepiness for any cause. The Urban Dictionary lists narcolepsy as a tendency to fall asleep, whereas really, narcolepsy is a neurological condition characterized by loss of orexin neurons. That only occurs in around 3 in 10,000 people. Yet if you ask the Australian population, around one in two people report being more tired or sleepy than what they expect to be. So clearly, they don’t all have narcolepsy, and we need to do better in health care, differentiating these different causes of sleepiness.

Some of the other causes of sleepiness that get sent to me as potentially narcolepsy are sleep disorders such as sleep apnea or other central disorders of hypersomnolence, such as idiopathic hypersomnia, sleepiness associated with other conditions like depression or medications that might be used for depression or other psychiatric illnesses.

Sleepiness and fatigue are also associated with medical disorders. I do see a number of people with chronic fatigue who get sent to me with maybe do they have narcolepsy as well? No, they haven’t got two conditions. They’ve just got sleepiness that’s occurring as part of their fatigue syndrome.

As a clinician, there are some clues that I look forward to help differentiate sleepiness. It is tricky because unfortunately, we don’t have good tests to further classify sleepiness, and tests like a multiple sleep latency test are pretty non-specific. I can show that someone’s sleepy, but it won’t tell me why they’re sleepy. But those clinical clues that I look for, one is the presence of post exertional malaise (PEM) that sense of tiredness or sleepiness made worse by exercise. Now, that’s not really a feature of narcolepsy, but is one of the characteristics of fatigue syndromes. The other feature that I find helpful is variation in sleepiness symptoms. Typically, narcolepsy symptoms, once they’re established, remained fairly stable across months, years, the rest of people’s life, whereas sleepiness associated with, for example, depression might vary, wax and wane and have periods where it’s worse periods and when it’s a bit better. The same for sleepiness associated with other medical conditions.

So I hope this is helpful and really wanted to make the point that not all sleepiness is narcolepsy. We need to think about not just using that term narcolepsy to describe all causes sleepiness and consider other potential causes for sleepiness.

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