Sleep Self-Regulation Using Mental Imagery

Assessed using the Pittsburgh Sleep Quality Index (PSQI; Buysse et al, 1989).The PSQI includes 19 items that assess sleep quality, hours of sleep, sleep onset length, sleep efficiency, sleep disturbances, use of medication and daytime. Item ratings are recoded and combined to form seven component scores. These scores are then summed into a global score ranging from 0(no difficulty) to 21(severe difficulties in all areas). Daily sleep quality was assessed with five PSQI items.

The Sleep Hygiene Index (Mastin et al, 2006). Respondents rate on a scale from 1 (never) to 5 (all the time) how frequently they engaged in 13 behaviors (e.g. "I take naps lasting two or more hours"). Ratings were summed to provide a total negative sleep habit frequency score.

Participants rated their sleep self-efficacy with the item, "how confident are you that you can take the actions necessary to get a good sleep tonight?" Sleep response efficacy was rated with the item "how confident are you that you will actually get a good sleep tonight?" ratings ranged from 1 (not at all confident) to 10 (very confident), and they were summed; r=.69, p<.01 at baseline and r=.20, p<.05 at final follow-up.

The Pre-sleep Arousal Scale (Nicasso et al, 1985) includes an 8-item somatic subscale (e.g. "how often in the last week before bed have you had a tight, tense feeling in your muscles?") and an 8-item cognitive subscale (e.g. "how often in the last week before bed do you review or ponder events of the day?"). Ratings range from 1 (not at all) to 5 (extremely) and are summed to generate scores.

Measure adapted from the Vividness of Imagery Questionnaire (White et al, 1978). Participants rated the vividness of the following images: (1) putting things into a bag, (2) releasing a bag, (3) getting home from work, (4) relaxing at home, (5) their night-time routine, (6) the time that they visualised going to bed, (7) the environment of their bedroom, (8) the details of the bed they are sleeping in, (9) the image of themselves falling asleep. Response options were: 1 (no image at all) 2 (vague and dim), 3 (somewhat vivid), 4 (reasonably clear), and 5 (perfectly clear and vivid).

An adaptation of the action planning measure developed by Luszczynska and Schwarzer (2003) was used. The items included: "I have made a detailed plan for (1) how I am going to wind down before going to sleep (2) how I am going to prepare for bed (3) how I am going to prepare the place where I will sleep, and (4) the time when I go to sleep". Responses ranged from 1 (not at all) to 7 (very much); ratings were summed to generate scores.