Acute dopamine-agonist treatment in restless legs syndrome: effects on sleep architecture and NREM sleep instability.

STUDY OBJECTIVES: To analyze cyclic alternating pattern (CAP) in restless legs syndrome (RLS) and the eventual changes induced by the acute administration of pramipexole. SETTING: Sleep clinic in a scientific research institute. INTERVENTIONS: Placebo or pramipexole 0.25 mg. METHODS: Thirty-four patients were included: 19 patients received 0.25 mg of pramipexole and 15 were given placebo. The control group included 13 normal subjects. Nocturnal polysomnography was carried out in all subjects, and a second night was recorded after pramipexole or placebo was administered to patients with RLS. Sleep stages, CAP, and leg movement activity were scored following standard criteria. MEASUREMENTS AND RESULTS: At baseline, rapid eye movement sleep latency was significantly longer in patients with RLS than in normal control subjects, and the periodic leg movement during sleep index (PLMS) was also significantly higher. On the contrary, many CAP parameters appeared to be significantly different, with a general increase in CAP rate in patients with RLS. Acute administration of pramipexole induced moderate changes in sleep architecture (increased number of stage shifts/h, sleep efficiency, and percentage of stage 2 sleep; decreased wakefulness after sleep onset; and a lower PLMS index. No effects of treatment on CAP were observed. CONCLUSION: Patients with RLS show significant abnormalities in sleep microstructure, represented by an excessive sleep instability/discontinuity. Acute pramipexole administration seems to exert no action on these abnormalities; the moderate effects seen on sleep architecture might be interpreted as the beneficial consequence of the removal of presleep RLS symptoms and PLMS.

Measuring the error in sleep estimation in normal subjects and in patients with insomnia.

The aims of this study were to measure the error in sleep estimation in normal controls and subjects with primary insomnia to establish the minimum amount of sleep needed for reliable subjective estimation and to depict the distribution of the error in sleep estimation in both groups. A two-step retrospective (study 1) and prospective (study 2) validation study was carried out. Study 1 included 288 normal subjects [176 females and 112 males, mean age 58.5 years, standard deviation (SD) 7.23]. Study 2 included 159 patients (98 females and 61 males; mean age 49.1 years, SD 12.71) with primary insomnia. Participants underwent a full-night polysomnographic study, followed by a morning assessment of subjective sleep parameters. A misperception index (MI) was computed using the following formula: MI = [objective total sleep time (oTST)-subjective total sleep time (sTST)]/oTST. The statistical properties of this index were analysed in detail in both groups. In controls, the Bland-Altman test demonstrated the reliability of this index for values of oTST >120 min. Healthy subjects estimated their sleep time correctly, while insomniacs largely underestimated their sleep time. Statistical analysis of the distribution of MI in insomnia patients disclosed the presence of two subgroups, one with moderate sleep misperception (132 patients) and the other with high sleep misperception (27 patients). The latter presented MI values >or=0.9, exhibiting statistical properties different from those with MI <0.9 and from normal subjects. The MI gives a reliable and immediate description of sleep misperception in healthy and insomnia subjects. Its application supports the existence of the high misperception of insomnia as a separate pathological entity.