Objectives: The objective of the present study is to identify which underlying beliefs about the impact of sleep on health may motivate change in sleep behavior. Design: A cross-sectional study conducted between 2012 and 2014. Setting: Data were from the Sleep and Healthy Activity, Diet, Environment, and Socialization (SHADES) study conducted in Philadelphia, PA, and its surrounding regions. Participants: Participants consisted of N = 1007 community-dwelling adults age 22–60. Measurements: Respondents indicated behaviors they could improve on to facilitate sleep and their corresponding readiness to change. They were also asked items from the Sleep Practices and Attitudes Questionnaire (SPAQ) regarding the degree to which they agree with whether “not getting enough sleep” can impact a variety of health factors. Results: In adjusted analyses, stage of change was associated with degree of agreement that insufficient sleep can cause sleepiness (odds ratio [OR] = 1.17, P = .035), weight gain (OR = 1.20, P < .0005), heart disease (OR = 1.21, P = .001), cholesterol (OR = 1.13, P = .047), hypertension (OR = 1.16, P = .014), moodiness (OR = 1.42, P < .0005), decreased energy (OR = 1.30, P = .002), absenteeism (OR = 1.13, P = .007), decreased performance (OR = 1.20, P = .003), concentration/memory problems (OR = 1.23, P = .004), diabetes (OR = 1.14, P = .042), and feeling tired (OR = 1.39, P < .0005). When sleep duration was added to the model, significant associations remained for all except cholesterol. When accounting for insomnia, significant associations were maintained for only weight, moodiness, performance, diabetes, and tiredness. Conclusions: Degree of belief that insufficient sleep can cause outcomes such as moodiness, occupational problems, and health problems may impact whether an individual is contemplating/attempting to change their sleep-related behaviors. Targeting these key messages about the associations between sleep health with moodiness and weight gain in informational material may enhance education/outreach efforts aimed at adults.