What are common sleep problems in multiple sclerosis?

More than half of MS patients report sleep problems during the course of the disease. Common sleep problems include insomnia, breathing disorders during sleep and restless leg syndrome. The reasons for sleep problems in multiple sclerosis are as varied as the disease itself.‍

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Insomnia

Insomnia refers to problems falling asleep, sleeping through the night or waking up too early. Insomnia affects almost 50% of MS patients.The causes of insomnia are very diverse. On the one hand, typical symptoms of multiple sclerosis such as pain, spasticity, bladder dysfunction, especially nocturia, and depression can lead to sleep disorders. Stress and mental tension can also lead to sleep problems. On the other hand, basic MS therapies can cause sleep disorders. For example, it is assumed that cortisol reduces the amount of the sleep hormone melantonin in the blood, which is largely responsible for the sleep rhythm [1,2].

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Breathing disorders during sleep

Multiple sclerosis is a chronic inflammatory disease of the central nervous system. As such, it is very complex, which is why it is also called the disease of a thousand faces. Respiratory disorders are more common in MS patients than in people without multiple sclerosis. Sleep-disordered breathing (SDB) includes interrupted breathing (not breathing) and loud and/or irregular breathing sounds.  Breathing disorders occur in at least one in five patients. The increased incidence of sleep-disordered breathing is thought to be multifactorial and is caused by the neurological effects of MS lesions, respiratory muscle impairment and drug treatment.There are several potential reasons why sleep-disordered breathing (SDB), including obstructive sleep apnea (OSA) and central sleep apnea (CSA), is more prevalent in patients with multiple sclerosis:

• Inflammation
  ‍Chronic inflammation in MS can contribute to upper airway narrowing and instability, which can lead to obstructive events during sleep. [4]
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• Weakness of the respiratory muscles
  ‍MS can lead to weakness of respiratory muscles such as the diaphragm and intercostal muscles, reducing their ability to maintain adequate ventilation during sleep. [4]‍
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• Brainstem lesions
  ‍MS lesions in the brainstem can affect the neural control of breathing during sleep, leading to central apneas and hypopneas. Patients with brainstem involvement have a significantly higher rate of SDB compared to patients without brainstem lesions [5].
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• Autonomic dysfunction
  ‍Autonomic dysregulation due to MS brain lesions can affect upper airway patency and mechanisms to control breathing during sleep. [4]
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• Effects of medications
  ‍Certain medications used to treat MS, such as corticosteroids, antidepressants and muscle relaxants, can dampen respiratory drive or cause sedation, increasing the risk of SDB. [4]‍
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• Overweight & obesity
  ‍Although not a direct cause, the increased prevalence of obesity in MS patients due to factors such as reduced mobility and steroid use is a risk factor for obstructive schizophrenia.

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Restless legs syndrome

Restless legs syndrome (RLS) describes the irresistible urge to move the legs. Restless leg syndrome is often accompanied by unpleasant sensations such as tingling, crawling or pain, especially at rest or when lying down. RLS is not a symptom of MS, but it is a common accompanying symptom. RLS occurs in around 23-26% of MS patients, compared to 5-15% in the general population [6,7].‍The exact cause of the increased prevalence of RLS in MS patients is not yet known. Researchers suspect that it is related to the nerve damage and demyelination caused by MS, which may affect dopaminergic pathways [7]. RLS in MS patients is associated with poorer sleep quality, increased fatigue, daytime sleepiness, depression and reduced quality of life.Factors that influence the occurrence of RLS in MS patients include

• gender
• the severity of MS symptoms
• the degree of disability
• lesions of the spinal cord

Studies have shown that RLS is more likely to occur in people who are female, have more MS symptoms, have higher disability scores and have spinal cord lesions [8].