Circadian rhythm of periodic limb movements and sensory symptoms of restless legs syndrome

The symptoms of restless legs syndrome (RLS) worsen while patients are sitt ing or lying and also worsen at night. The current study was designed to de termine if the periodic limb movements (PLMs) and sensory symptoms of RLS a re modulated by an independent circadian factor. We recorded sleeping and w aking PLMs and waking sensory symptoms in eight volunteers with RLS for 3 s uccessive nights and days, starting with a polysomnographic recording of 2 nights, followed by a third night of sleep deprivation and the day after sl eep deprivation. This study showed that both the PLMs and sensory symptoms were worst at night with a maximum for both between midnight and 1:00 AM an d a minimum between 9:00 and 11:00 AM. Sleep and drowsiness had a tendency to worsen PLMs and sensory symptoms after the night of sleep deprivation. C ircadian temperature curves were normal in all four patients with adequate data collection. The highest PLM counts occurred on the falling phase of th e circadian temperature curve whereas the lowest PLM counts occurred on the rising phase of the curve. We conclude that the PLM and sensory symptoms i n RLS are influenced by a circadian rhythm, and that the "worsening at nigh t" criterion of the RLS Definition Criteria is, at least in part, distinct from the "worsening while lying or sitting" criterion.