Mini-Med at McGill: Question and Answer Corner

Mini-Med Study Corner

Sleep Disorders: To Sleep, Perchance to Dream....
Dr. John Kimoff

Written Question and Answer Section:

1. What is the relationship between Sleep Apnea and Parkinson's Disease?

Patients with Parkinson’s Disease may have a number of sleep difficulties. Sleep apnea can occur, though it is unknown whether it is more common among Parkinson’s patients than in the general population. There may be symptoms of Restless Legs Syndrome, and there may be complaints of disrupted or poor-quality sleep in some patients which are not linked to any clearly identifiable cause.

One particular manifestation, which may develop in patients with a known diagnosis of Parkinson’s, or may occur up to several years before the onset of other Parkinson’s manifestations, is REM (Rapid Eye Movement) Sleep Behaviour Disorder. In this condition, affected individuals have physical activity during sleep related to dream content – in effect, “acting out their dreams”. This may involve vocal and physical activity, with the latter sometimes being quite violent, and potentially injurious to the patient or bed-partner. This condition is associated with a reduction in the normal inhibition of muscle activity that occurs during REM sleep. The diagnosis is made based on the clinical history and an overnight sleep study. While this condition is strongly associated with Parkinson’s, it may occur in the absence of an identifiable cause, in other medical conditions or as a side effect of some medications, particularly anti-depressants.

2. Would you please comment on the connection, if any, between Narcolepsy, Restless Leg Syndrome and Sleep Apnea?

While more than one sleep disorder can be observed in a single individual, this is relatively uncommon. There are no direct links between the three conditions mentioned. However all three can result in excessive daytime sleepiness. In Narcolepsy, the sleepiness is due to changes in a brain transmitter protein called Orexin or Hypocretin, which is important in maintaining wakefulness and alertness. In Restless Legs Syndrome, daytime sleepiness occurs because the symptoms typically begin when the patient goes to bed and prevent the onset of sleep for up to several hours. If the person has to get up at a fixed hour to go to work, this results in a reduced time for sleep, and therefore daytime sleepiness. In obstructive sleep apnea, when the breathing passage blocks during sleep, blood oxygen falls and breathing efforts increase, which then provokes a disruption of sleep or “microarousal”, causing the airway muscles to activate and re-open the blocked passage. While microarousal is therefore an important and life-saving response, when it occurs repeatedly over the course of the night, sleep is very fragmented, and therefore non-restful, leading to daytime sleepiness.

3. Are there any lifestyle factors that can either prevent someone from developing Sleep Apnea, or alternately, predispose one to this problem?

While not all sleep apnea patients are obese, obesity is by far the most important “modifiable” risk factor for sleep apnea. Weight loss will improve and in some cases, cure sleep apnea. Thus all of the lifestyle factors (diet, exercise, etc.) which can help control body weight can be beneficial for sleep apnea, while conversely, increasing weight will be associated with worsening of apnea.

Alcohol relaxes the upper airway muscles and dulls the arousal response to apneas; thus drinking can worsen sleep apnea both by causing more apneas, and making individual apneas longer, thereby associated with lower oxygen levels.

In up to half of patients, sleep apnea is worse lying on the back than on the side. Thus strategies which help to avoid the supine position may be helpful for some patients. Various approaches have been used including sewing a ball into the pyjama top, use of a large pillow, sleeping with a back pack or positioning belt.

In patients with very mild sleep apnea, there is some evidence that training of the upper airway muscles uses speech exercises, or playing a wind instrument such as the digeridoo, can be beneficial. However for moderate to severe sleep apnea, these approaches are not effective, and for in some severe apnea patients who may already have over-stressed upper airway muscles, could be detrimental.

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