When MS Feels Like Narcolepsy
The daytime sleepiness and fatigue that MS is famous for are perhaps the most common symptom experienced by people with MS. Pathological fatigue occurs when, upon awakening, you still feel extremely tired, unrefreshed, and lethargic.
While this is normal across the board for people with MS, it can also point to the possibility that a more rare sleep disorder might have gone undetected: narcolepsy.
Let’s unpack what it means to have narcolepsy.
What is narcolepsy?
Narcolepsy is a neurological sleep disorder categorized as a hypersomnia.
The brains of those with narcolepsy struggle to regulate sleep-wake cycles. For these people, wakefulness can be disrupted by sudden and compelling periods of rapid-eye-movement (REM) sleep during the day. Meanwhile, nighttime sleep may be disrupted by periods of wakefulness.
During a regular sleep cycle (of which we have 4 or 5 every night), most of us fall into REM sleep about 90 minutes in. However, in someone with narcolepsy, REM sleep can occur almost immediately upon falling asleep.
Narcolepsy is typically identified by four main symptoms (what they call the narcolepsy tetrad):
- Excessive daytime sleepiness: not just being drowsy, but having an irresistible need to sleep.
- Cataplexy: the postural “sleep attack” that is characteristic in type 1 narcolepsy. Cataplexy can involve partial losses of muscle tone — as in slurred speech — or complete and involuntary falls due to sudden weakness in the body, arms or legs. Cataplexy may resemble sudden sleep, but usually the person is awake and aware.
- Sleep paralysis: a brief inability to speak or move upon awakening, sometimes accompanied by hallucinations.
- Hallucinations: whether at sleep onset — hypnagogic — or upon awakening— hypnopompic — these bizarre, dreamlike experiences are stunningly real making it hard to know whether one is asleep or awake.
Could someone with MS also have narcolepsy?
Narcolepsy is a lifelong neurological disorder with no cure. Typically, it develops in children and young adults.
For these reasons alone, it’s plausible that MS and narcolepsy could be linked.1 Sleep medicine physician Robert S. Rosenberg suggested in an interview in Sleep Review in 2016 that “if the patient is presenting with significant sleepiness, it is not uncommon for …narcolepsy to be overlooked.”
It makes sense. A neurologist, upon reviewing films and spinal tap results, may overlook the possibility of a separate sleep disorder if a clear diagnosis of MS, following the McDonald protocol, can be established.
MS is considered, by some, to be a less common cause for developing narcolepsy. In the book Multiple Sclerosis Therapeutics, MS is cited as the fourth most common cause of narcolepsy “due to a medical condition” by authors Scagnelli and Goldman.2
How might MS cause narcolepsy?
Scagnelli and Goldman describe the link as related to lesion location; demyelination of the hypothalamus may be the culprit.
Scagnelli and Goldman also hint at a genetic relationship. They point out that half of MS patients and nearly all narcolepsy patients are “DR2 positive” and share a common genetic bond: DQB1*0602. However, other research published in 2017 seems to refute this3:
“Our series did not suggest a significant relationship between narcolepsy, MS and HLA-DQB1*06:02. Therefore, this study showed that narcolepsy in MS patients may yet be coincidental in the presence of HLA-DQB1*06:02, based on the most widely-used scale for narcolepsy (ESS) and neurophysiological studies (PSG and MSLT). Although the small number of MS patients with HLA-DQB1*06:02 could influence our findings, these data suggest that HLA-DQB1*06:02 alone is not sufficient for MS patients to develop narcolepsy.4”
To be safe: research is ongoing and inconclusive at this time.
Should people with MS be concerned?
Narcolepsy is considered rare. Fewer than 200,000 cases are reported annually in the US. Only 1 in 2,000 individuals with a genetic predisposition to narcolepsy develops it. On odds alone, your chances of having both MS and narcolepsy are pretty slim.
But if you experience any of the following symptoms, you are best advised to speak with your MS specialist, as diagnostic sleep assessments can be performed to identify a hidden sleep disorder like narcolepsy:
- You feel weak or you lose muscle coordination (especially in the neck or the knees) when you experience a sudden emotional response (laughter or fright, as examples).
- You struggle to discern dreams from waking life.
- You experience sleep paralysis. While it can be a somewhat common event in the general population, sleep paralysis shouldn’t be a regular feature of your sleep life.
- You learn from a loved one or cohort that you behave unusually while awake, as if in a trance. Automatic behavior occurs when a person loses conscious awareness of activities and surroundings while enacting what appears to be normal behavior.
- You abruptly fall asleep at inappropriate times (while waiting at a stoplight, during a loud movie, while attending a live event, or during an active conversation with another).
These symptoms may or may not lead to a narcolepsy diagnosis. However, if you have sleep troubles in general, they may reveal sleep-related problems or medical issues you need to address anyway. Which begs the reminder: not everything is MS.
At any rate, treatments for narcolepsy are fairly limited. Many MS patients are already using them for fatigue (modafinil, armodafinil, or methylphenidate). Gaining a second diagnosis is not likely to yield more or better options for treatment.
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