The intervention group had better CPAP use ( higher daily CPAP usage by 2 h/d [ Cohen d = 1.33 , P < .001 ] , a fourfold increase in the number using CPAP for 70 % of days with 4 h/d [ P < .001 ] ) , and greater improvements in daytime sleepiness ( ESS ) by 2.2 units ( P = .001 ) and treatment self-efficacy by 0.2 units ( P = .012 ) compared with the control group .