Pregabalin improved sleep maintenance , demonstrated by reductions in WASO ( -27.1 min vs placebo [ P < 0.0001 ] ; -26.9 vs pramipexole ) and number of awakenings after sleep onset ( -2.7 vs placebo ; -7.9 vs pramipexole [ P < 0.0001 ] ) by polysomnography , and an increase in subjective total sleep time ( 30.8 min vs placebo [ P < 0.0001 ] ; 26.8 vs pramipexole ) .