6.33 Sleep quality. A random sample of 871 students between the ages of 20 and 24 at a large midwestern university completed a survey including questions about their sleep quality, moods, academic performance, physical health, and psychoactive drug use. Sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI), with students scoring less than or equal to 5 on the index classified as optimal sleepers, those scoring a 6 or 7 classified as borderline, and those scoring over 7 classified as poor sleepers. The following table looks at the relationship between sleep quality classification and the use of over-the-counter (OTC) or prescription (Rx) stimulant medication more than once a month to help keep awake. 17 SLEEPPQ Use of OTC/RX Meds to Wake > 1x/Month Yes No Optimal Borderline Sleep Quality on PSQI Index Poor 37 53 84 266 186 245 What do the data say about differences in sleep quality for those who use over- the-counter or prescription stimulant medication more than once a month to keep awake and those who don't?