At month 1 , suvorexant ( 517 patients in the efficacy population ) showed greater efficacy than placebo ( 254 in the efficacy population ) in improving sTST ( 387 min vs 160 min ; difference 227 , 95 % CI 164 to 290 ; p < 00001 ) and sTSO ( -180 min vs -84 min , difference -95 , -146 to -45 ; p = 00002 ) .