Parkinson's disease is a disorder of the central nervous system that causes a loss of cells in the part of the brain that controls movement. People with Parkinson’s disease experience a range of symptoms, including tremor (shaking), rigidity (stiffness), slowness of movement, and problems with balance and coordination. They may also have memory problems, depression, and sleep complaints. Parkinson's disease is both chronic and progressive, meaning that once it occurs it does not go away and symptoms generally get worse over time; the rate or speed of progression is different from person to person.
Parkinson’s disease can be idiopathic, meaning that it occurs with no known cause. In this case it probably develops by some interaction between a person's genes and their environment. It can also be secondary, occurring as a result of another disease, exposure to certain drugs, or as a result of repeated head trauma. According to the Parkinson's Disease Foundation, between 15 and 25 percent of people with Parkinson's have a relative with the disease, suggesting that for some people it may be inherited. Age is also a risk factor, with older people being more likely to develop Parkinson’s disease than younger people, according to the National Institute of Neurological Disorders and Stroke at the National Institutes of Health. Exposure to toxins may also play a role but the nature of that role is not well understood.
Sleep problems may be an early sign of Parkinson’s disease, even before motor symptoms have begun. Some of the common sleep problems for Parkinson’s patients include:
A recent study by UCLA researchers found an association between Parkinson's disease and narcolepsy, a disorder caused by the brain's inability to regulate sleep/wake cycles normally. The study revealed that patients with Parkinson's disease and those with narcolepsy both display a loss of orexin/hypocretin (Hcrt) cells in the brain and that loss of Hcrt cells is correlated with severity of PD. However, there is no reason to believe that narcolepsy patients are at increased risk of developing Parkinson's disease. According to study author Jerry Siegel, PhD, professor of psychiatry and biobehavioral sciences at the Semel Institute for Neuroscience and Human Behavior at UCLA, the cause of the hypocretin cell loss in Parkinson's is likely to be quite different from the cause of this cell loss in narcolepsy.
There may also be a connection between REM sleep behavior disorder (dream–enacting behaviors during sleep) and the subsequent development of Parkinson’s disease. In one study, researchers found that up to 75% of patients with REM behavior disorder went on to develop a Parkinsonian disorder, presumably Parkinson’s disease. In addition, people with Parkinson’s disease are at higher risk for restless legs syndrome (RLS) and periodic leg movement disorder, two conditions that may seriously disrupt sleep. However, there is no evidence that RLS or PLMD are risk factors for Parkinson’s disease.
In addition to sleep problems, people with Parkinson's disease often experience sleepiness during the daytime. In fact, one study found daytime sleepiness in 76% of Parkinson’s patients. These sleep-related symptoms can have a major impact on quality of life for Parkinson’s patients and treatment for these problems should be integrated with their therapeutic regimens.
Because of the mystery surrounding the origin of Parkinson’s disease, a great deal of research has been done on this problem. We know that the symptoms of Parkinson’s are primarily the result of the gradual loss of dopaminergic cells (neurons that release dopamine, a neurotransmitter that activates dopamine receptors) in the brain. Some Parkinson’s research has focused on the relationship between Parkinson’s and both the timing and duration of sleep. For example, a 12-year study by researchers at the National Institute of Environmental Health Sciences of the U.S. National Institutes of Health found that among nearly one million nurses, working the night shift was associated with a lower risk of Parkinson’s disease. They also found that long sleep (sleeping 9 hours or more) was associated with a higher risk.
People with Parkinson’s disease have a shortened life expectancy and may find it difficult to maintain their quality of life. Striving to maintain healthy sleep habits can help Parkinson’s patients with both the physical and psychological symptoms of their disease.
The hallmark symptoms of Parkinson's disease are tremor, rigidity, slow movements and problems maintaining balance. Other symptoms may include difficulty walking, talking, eating, or carrying out other simple tasks. Parkinson’s patients also suffer incontinence, constipation, and sexual dysfunction and are at higher risk for developing depression, anxiety, memory, and emotional problems.
Because Parkinson's disease is associated with "sleep attacks," patients may be suddenly overcome with drowsiness and fall asleep – regardless of what they are doing. This is particularly dangerous for those patients who are still driving, operating equipment (even kitchen and lawn equipment or other tools) or caring for dependents.
Not everyone with Parkinson's disease develops all or even most of the symptoms described above. The rate at which the disease progresses is also variable, with some people experiencing a rapid worsening of symptoms shortly after being diagnosed and others spending many years with only mild symptoms.
With Parkinson’s disease, there is a gradual loss of dopaminergic cells in the brain. There is no treatment for slowing or reversing this process, but there are drugs used to treat the symptoms that result. These drug therapies can dramatically improve quality of life for Parkinson's patients. Here are some of the most common types:
Following diagnosis and the start of treatment, Parkinson's patients may experience a reduction of symptoms. This is called a "honeymoon." After a few years, the honeymoon ends and symptoms intensify, especially the motor symptoms.
People with Parkinson’s disease often have excessive daytime sleepiness. They also fall into REM sleep more quickly than the average person, according to their brain activity. These are both symptoms of narcolepsy and although there is no evidence that narcolepsy is a risk factor for Parkinson’s disease or vice versa, sleep-related symptoms in patients with Parkinson’s may be successfully treated with drugs that are used for narcolepsy, including stimulants for daytime sleepiness and sleeping medication for nighttime sleep. Bothersome dream-enacting behaviors often respond favorably to clonazepam, a sedative medication.
As Parkinson’s disease progresses and symptoms get worse, sleep problems may become more serious. For example, pain and uncontrollable movements may cause severe insomnia. Nighttime symptoms may be improved by taking Parkinson’s medication later in the day or by taking hypnotic sleep aides.
Insomnia may also be caused by certain medications used to treat Parkinson’s symptoms. In that case, taking medication earlier in the day may improve sleep. Keep in mind that any change in medication – including the addition of sleep aides or the timing of administration - should be prescribed by a physician. Sleep aides you can buy without a prescription usually contain diphenhydramine, an anti-histamine, which blocks absorption of dopamine.
Daytime sleepiness may also increase as Parkinson’s disease progresses. Using stimulant or alerting medications during the day may prevent sleep attacks and help patients avoid excessive napping, which may contribute to insomnia. In addition to drug therapies, behavioral techniques should be used for sleep and sleepiness problems in Parkinson’s patients.
Coping with Parkinson’s disease isn’t easy and will depend on the type and severity of the symptoms. However, there are certain things you can do to minimize symptoms, including taking medication as prescribed and getting healthy sleep. Here are some sleep tips for Parkinson’s patients:
If the Parkinson’s disease is not advanced then behavioral therapies may be useful to try. Behavioral techniques may include changing attitudes about sleep, learning new sleep habits, and sticking to a regular sleep schedule.
Parkinson’s patients are encouraged to spend time outdoors and to exercise each day, preferably in the morning or shortly after waking. Light therapy may also help normalize the sleep/wake cycles of Parkinson’s patients, especially those who may be unable to spend time outdoors.
In general, the quality of life for patients with Parkinson’s disease may be optimized with support and recognizing the opportunities to make lifestyle adjustments. That is why support groups for patients, family members and caregivers can be important. They introduce the participants to caring and supportive individuals and you can learn what decisions others have made and what works best. This can help avoid getting "stuck" at one stage and can help to take advantage of a useful idea. Support groups may be in your local community or you may be able to participate in information exchanges online. Visit the National Parkinson Foundation support group information page to find support resources in your area.
Reviewed by David Rye, MD, PhD, and Mark Mahowald, MD.