Whether Parkinson’s disease (PD) patients shake in their sleep is a common concern. PD primarily affects movement, manifesting with symptoms like rigidity, slowness of movement (bradykinesia), and the characteristic resting tremor. This resting tremor, often described as a “pill-rolling” motion, is one of the most recognizable signs of the condition. However, during sleep, the familiar waking tremor generally disappears, replaced by other, often more disruptive, motor and non-motor issues.
The Nature of the Parkinsonian Tremor
The involuntary shaking associated with Parkinson’s disease is known as a resting tremor because it is most pronounced when the affected limb is completely relaxed and at rest. This tremor typically lessens or stops entirely when the person performs a purposeful movement with that limb. This pattern is distinct from other types of tremors and provides a clue as to why the shaking stops during sleep.
The resting tremor generally ceases or significantly diminishes once a person enters the stages of sleep. During both non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, the brain’s motor control centers operate differently, effectively suppressing these involuntary movements. In some patients, the tremor may persist momentarily during the transition into light sleep or when briefly waking, but its amplitude is often reduced by up to 50% compared to a waking state.
Motor Issues That Replace Tremor During Sleep
While the resting tremor itself typically subsides, other motor disturbances frequently emerge, often causing significant sleep fragmentation for the person with PD and their partner. The most disruptive of these is REM Sleep Behavior Disorder (RBD), a condition where the normal muscle paralysis that occurs during REM sleep is absent. This lack of muscle atonia allows individuals to physically act out the content of vivid and often frightening dreams.
These movements are complex, sometimes violent actions like punching, kicking, or yelling, unlike the rhythmic resting tremor. RBD is highly correlated with Parkinson’s disease and can even precede the motor symptoms of PD by many years. Another motor symptom that disrupts sleep is dystonia, involving sustained muscle contractions causing twisting or abnormal postures. This often occurs as early-morning cramping, particularly in the feet, when nighttime dopaminergic medication effects have worn off and dopamine levels are lowest.
Other Common Non-Motor Sleep Disruptions
Beyond specific motor events, the sleep of a person with Parkinson’s disease is often severely fragmented by non-motor symptoms. Difficulties falling asleep and staying asleep are common complaints. Insomnia, or sleep fragmentation, is often linked to the inability to reposition in bed due to rigidity and slowness (nocturnal akinesia), or the frequent need to use the bathroom.
Restless Legs Syndrome (RLS) is another common issue, characterized by an uncomfortable urge to move the legs, often accompanied by unpleasant sensations relieved by movement. This sensation makes falling asleep difficult and can lead to leg movements throughout the night. Frequent nighttime urination, known as nocturia, forces patients to wake up multiple times, contributing to poor sleep quality and excessive daytime sleepiness.
Strategies for Managing Sleep Disturbances
Addressing sleep problems in Parkinson’s disease involves a comprehensive approach that targets the specific cause of the disruption. Optimizing the timing and dosage of PD medications is often the first step, as using a long-acting dopaminergic agent or controlled-release levodopa at bedtime can help manage nocturnal motor symptoms like rigidity and early-morning dystonia. Certain medications, such as clonazepam, have been shown to be effective in reducing the episodes of dream enactment associated with REM Sleep Behavior Disorder in a high percentage of patients.
Non-pharmacological interventions are also beneficial, starting with good sleep hygiene practices like maintaining a consistent sleep schedule and ensuring the bedroom is dark and quiet. Regular physical activity, particularly exercise timed earlier in the day, has been shown to improve sleep quality in PD patients. Patients dealing with severe or persistent sleep issues should consult a neurologist or a sleep specialist for a thorough evaluation, which may include a sleep study (polysomnography) to diagnose underlying conditions like RLS or sleep apnea.