Restless Legs Syndrome (RLS) | Why Can't I Stop Moving My Legs at Night?

The primary symptom of Restless Legs Syndrome (RLS), also known as Willis-Ekbom disease, is an overwhelming, often irresistible urge to move the legs. This is not a simple case of fidgeting. The urge is triggered by abnormal, unpleasant sensations deep within the limbs. Individuals describe these feelings in various ways, most commonly as a "creepy-crawly" feeling, but also as itching, pulling, throbbing, aching, or tugging. It is important to clarify that these sensations originate from within the nervous system, not on the skin like a typical itch. They arise from a complex dysfunction in how the brain uses a neurotransmitter called dopamine. Dopamine pathways are crucial for controlling muscle movement, and in RLS, dysregulation in these pathways, particularly in a brain region called the substantia nigra, leads to the sensory discomfort and motor compulsion that define the disorder. Moving the legs, such as by walking, stretching, or shaking them, provides temporary relief from this profound discomfort.

RLS symptoms are governed by two key patterns: they are triggered by periods of rest or inactivity and follow a distinct circadian rhythm. The uncomfortable sensations and the urge to move typically begin or worsen when an individual is sitting or lying down for an extended period, such as when watching a movie, sitting at a desk, or trying to fall asleep. Furthermore, the symptoms are most severe in the evening and at night. This nightly pattern is linked to the body's natural circadian cycles, including fluctuations in dopamine levels, which tend to dip in the evening. This combination means that RLS significantly disrupts the most crucial periods of rest, leading to difficulty initiating and maintaining sleep, which in turn causes daytime fatigue and impairs overall quality of life.

While the classic description of RLS centers on uncomfortable and strange sensations, a significant number of individuals do experience the symptoms as painful. The character of the sensation can range from a dull ache to a more severe, distressing pain. This variability depends on individual perception and the severity of the condition. Neurologically, the signals that the brain interprets as "creepy-crawly" or "itchy" are processed in sensory pathways that are closely linked with pain pathways. Therefore, it is plausible that for some individuals, the intensity of these signals crosses a threshold and is perceived by the brain as pain.

Augmentation is a serious complication that can arise from the long-term use of certain medications for RLS, particularly dopamine agonists. It refers to a paradoxical worsening of symptoms caused by the treatment itself. In cases of augmentation, symptoms may start to appear earlier in the day, spread from the legs to the arms or trunk, become more intense, and provide less relief from movement. This occurs because the continuous stimulation of dopamine receptors can cause them to become less sensitive over time, creating a need for higher doses and ultimately leading to a rebound effect where the underlying condition becomes more severe.

RLS and Periodic Limb Movement of Sleep (PLMS) are distinct but often related conditions. RLS is a sensory-motor disorder characterized by the conscious urge to move the limbs while awake, driven by uncomfortable sensations. The key elements are the sensation and the voluntary, albeit compulsive, movement to relieve it. In contrast, PLMS involves involuntary, repetitive movements of the limbs, most commonly jerking or flexing of the legs, that occur exclusively during sleep. The individual is typically unaware of these movements. Over 80% of people with RLS also have PLMS, but the reverse is not true; many people have PLMS without experiencing the distinct sensory symptoms of RLS when they are awake. Therefore, RLS is defined by what you feel while awake, whereas PLMS is defined by what you do while asleep.