Sleep benefit in Parkinson's disease: time to revive an enigma?

Some patients with Parkinson's disease (PD) reportedly experience 'sleep benefit': an improved motor functioning upon awaking in the morning. In this questionnaire study, 114 out of 243 consecutive outpatients with PD (46.9%) subjectively experienced sleep benefit. Among those patients that regularly took an afternoon nap, 33.7% experienced sleep benefit after the nap as well. Between patients with and without sleep benefit, there were no differences in demographic or clinical variables, including age, disease duration, dopaminergic treatment, and nocturnal sleep quality. Sleep benefit remains an intriguing but elusive phenomenon, which deserves renewed attention and further research.