Can restless legs syndrome or periodic leg movements affect my sleep?
People with RLS may complain of varying degree of leg discomfort during the daytime. Some people may even experience problems with memory and concentration. However, many people are affected most significantly at bedtime as the symptoms are worse with inactivity and at night, and this makes it difficult to fall asleep. It is not uncommon for them to get up several times to walk around until symptoms are partially relieved.
On the other hand, PLMS occurs when the person is already asleep and can range in intensity from mild twitches to violent kicks. Although the peak of PLMS activity typically occurs in the early part of sleep, leg movements may be present for the entire night in more affected individuals. In the laboratory, PLMS is considered severe if it occurs 50 times or more per hour—especially if movement causes frequent brief awakenings (arousals) at least 25 times per hour. Generally, people with PLMS are not consciously aware of these awakenings, but if they occur very frequently, sleep may be severely disrupted resulting in excessive daytime sleepiness. PLMS may also result in the bed partner being kicked, sometimes violently, and wearing out of bedsheets on some occasions.
Can RLS/PLM cause sleep apnoea?
The answer is no, although the two conditions may interact.
- Obstructive sleep apnoea (OSA) is a condition where patients stop breathing very frequently during sleep, sometimes hundreds of times each night. Patients with OSA may sometimes have leg jerks during the night as a consequence of the upper airway repeatedly closing and opening. These leg jerks will disappear when the patient’s OSA is treated with continuous positive airway pressure (CPAP).
- Conversely, PLM, particularly if severe, can disrupt sleep and worsen mild OSA. Successful treatment of PLM can result in an improvement in OSA in such a case.
A sleep study can therefore be of value in certain patients, if another cause of sleep disturbance such as OSA is suspected, and needs to be confirmed.