Excessive daytime sleepiness in patients with Parkinson's disease: a polysomnography study

To investigate excessive daytime sleepiness (EDS) in patients with Parkinson's disease (PD), the reasons for which have not yet been clarified, polysomnography (PSG) and the Multiple Sleep Latency Test (MSLT) were performed in 46 patients with PD, and, in addition, PSG was performed in 30 healthy controls. Assessment included Epworth Sleepiness Score (ESS), Mini-Mental State Examination (MMSE), and Hamilton Test (HT) for depression. Fifty percent of PD patients reported EDS (ESS, 10 +/- 4.5 vs. 6.9 +/- 3.7; P = 0.01). Compared with controls, PD patients as a group had lower sleep efficiency (65 +/- 22 vs. 77 +/- 14; P = 0.03), a longer Stage 2 (73 +/- 12 vs. 67 +/- 12; P = 0.03), and a shorter rapid eye movement stage (8 +/- 8 vs. 17 +/- 8; P < 0.001). Clinical data and sleep characteristics were similar in PD with/without EDS. Of interest, patients treated with clonazepam (CLNZ) had lower EDS than those without CLNZ (ESS, 7.9 +/- 4.7 vs. 11.3 +/- 4.0; P = 0.03). These patients suffered less periodic leg movement during sleep (2.1 +/- 2.7 vs. 12.4 +/- 28; P = 0.04), which might explain the finding. No correlation was found between ESS, MSLT, and all other clinical features analyzed. In PD patients, according to the data obtained, severity of EDS does not depend on any specific clinical factor and the etiology is probably multifactorial. Paradoxically, PD patients treated with CLNZ were less sleepy than patients not treated with CLNZ.