Parkinson’s disease is a neurodegenerative disorder that gradually affects the nervous system and an individual’s overall movement. The age of onset for Parkinson’s is typically around middle or later life, typically around 60 years old. As an individual gets older, their risk to develop Parkinson’s increases as well. Some symptoms include tremors in one’s hands or fingers, bradykinesia (slowed movement), rigid muscles or muscle stiffness, impaired posture and balance, trouble performing automatic movements such as blinking or smiling, as well as speech and writing changes. Along with these symptoms, there are additional problems that individuals with Parkinson’s may experience, such as sleep disorders. Unfortunately, there is no cure for Parkinson’s disease, but there are medications available that can slightly improve symptoms (Parkinson’s disease – Symptoms and causes).
Common sleep disorders amongst individuals with Parkinson’s include insomnia and excessive daytime sleepiness. “Insomnia is the inability to fall asleep or maintain sleep” (Sleep and Parkinson’s Disease | Parkinson’s Disease). Individuals with insomnia may struggle with getting to sleep, staying asleep, moving around in bed, or waking up to go to the bathroom. Although the physiological explanation behind insomnia being common amongst those with Parkinson’s is not fully understood, many research studies have indicated that a Parkinson specific treatment, which mainly includes dopaminergic drugs, may be responsible for such symptoms. A particular study had a five year drug-naive group of patients with Parkinson’s, in other words these individuals were not treated with the dopaminergic drugs upon Parkinson incidence. Over the course of these five years, it was found that there was no significant increase in the prevalence of insomnia amongst these patients. However, when these same individuals were followed for five years after the original study was conducted and had initiated taking dopaminergic medication to treat their Parkinson’s disease, a significant increase in the occurrence of sleep insomnia symptoms was recorded (Stefani and Högl, 2019). Excessive daytime sleepiness can occur as a result of many factors amongst those with Parkinson’s disease, including being sleep deprived due to sleep disorders and problems experienced at night, or may be a symptomatic result of Parkinson’s disease treatment medications (Sleep and Parkinson’s Disease | Parkinson’s Disease). However, research related to Parkisnon’s disease dopamine agonist medications causing excessive daytime sleepiness is quite controversial. Nevertheless, research suggests that such treatment medications for Parkinson’s disease play a relevant role in causing excessive daytime sleepiness compared to pathophysiological mechanisms (Stefani and Högl, 2019). Whether experiencing insomnia or excessive daytime sleepiness amongst individuals with Parkinson’s disease, the importance of continuing research on the side effects or symptoms of certain treatment medications has been extensively stressed.
Circadian rhythms include rhythms such as the sleep-wake cycle, which are controlled by a “clock” or time-keeping mechanism in the brian. The sleep-wake cycle is heavily influenced by external parameters such as environmental light-dark cycles, time-zone shifts, aging, exercise, and melatonin. In general, older individuals’ circadian rhythms, specifically the sleep-wake cycle, tend to be affected in many ways. For instance, older individuals tend to go to bed earlier and wake up earlier (Sleep and Parkinson’s Disease | Parkinson’s Disease). For individuals with Parkinson’s disease, not only does the sleep-wake cycle get modified, but other circadian rhythms that affect motor, autonomic, cognitive, and psychiatric symptoms also are affected. Research studies have demonstrated that the circadian melatonin secretion rhythm is often reduced in those with Parkinson’s. Additionally, it is suspected that these reductions in melatonin rhythms may be due to insufficient exposure to light during the day. Individuals with Parkinson’s also experience similar modifications to their sleep-wake cycles similar to that of older individuals, and these modifications can also result in excessive daytime sleepiness. Research studies have suspected that these modifications to their sleep-wake cycle may be a result of dopaminergic drugs used to treat parkinson’s disease (Stefani and Högl, 2019).
Another common sleep disturbance amongst those with Parkinson’s disease is periodic leg movements of sleep (PLMS) and restless legs syndrome (RLS). RLS is an uncomfortable sensation in one’s leg that can be alleviated by moving your leg and PLMS is a jerking movement in the leg that typically occurs during sleep and often wakes the individual up (Sleep and Parkinson’s Disease | Parkinson’s Disease). Research studies have demonstrated that RLS may be a result of other Parkinson’s disease related symptoms including dystonia, which results in muscular spasms and abnormal posture, painful neuropathy, and nocturnal hypokinesia which is the inability to move during sleep resulting in difficulty getting up or laying down (Stefani and Högl, 2019). Additionally, RLS and PLMS may be a side effect of Parkinson treatment medications such as dopamine agonists (Sleep and Parkinson’s Disease | Parkinson’s Disease).
Although many individuals with Parkinson’s disease experience sleep disturbances, there is hope within future research to progress treatment medications without such side effects. Additionally, there are many tips such as maintaining a regular bedtime and rise time, getting bright light daytime exposure, taking shorter naps, avoiding heavy exercise six hours before sleep, avoiding heavy late night meals, and more to help individuals overcome sleep disturbances (Sleep and Parkinson’s Disease | Parkinson’s Disease).
References
Parkinson’s Disease – Symptoms And Causes. Mayo Clinic. 2020. [online] Available at: <https://www.mayoclinic.org/diseases-conditions/parkinsons-disease/symptoms-causes/syc-20376055> [Accessed 25 October 2020].
Sleep And Parkinson’s Disease. Parkinson’s Disease Clinic and Research Center. 2014[online] Available at: <https://pdcenter.ucsf.edu/sleep-and-parkinsons-disease> [Accessed 25 October 2020].
Simsek, L., 2020. Man In Black Jacket Sitting On Chair. [image] Available at: <https://www.pexels.com/photo/man-in-black-jacket-sitting-on-chair-3616835/> [Accessed 25 October 2020].
Stefani, A. & Högl, B., 2019. Sleep in Parkinson’s disease. Neuropsychopharmacology, 45(1), pp.121-128. https://doi.org/10.1038/s41386-019-0448-y
