Abstract This predictive study aimed to study insomnia and the predictors of insomnia among patients with heart failure including physiological hyperarousal, cognitive hyperarousal, Illness perception, extending bedtime, and daytime napping. Sample included 80 heart failure patients who visited a heart clinic at a tertiary hospital in Bangkok for followed-up treatment. Data were collected through administering of a demographic questionnaire, a heart failure record form, a sleep questionnaire, the pre-sleep arousal scale, the brief illness perception questionnaire, and the insomnia severity index. Data were analyzed by using descriptive statistic and multiple linear regression statistics. The Results had shown that approximately one-third (30%) of heart failure patients had moderate or severe insomnia. Most heart failure patients who had insomnia ( 5.79%) had mixed symptoms of insomnia (difficulty in initiating sleep, difficulty in maintaining sleep, and waking up too early). The results of the multiple regression analysis revealed that all independent variables (physiological hyperarousal, cognitive hyperarousal, Illness perception, extending bedtime, and daytime napping) jointly explained 35.4% of the variances in insomnia in heart failure patients (R2=.354, p=.0001). Cognitive hyperarousal and Illness perception were the variables found to be capable in predicting insomnia of heart failure patients (β = .378, p =.0001 and .341, p = .001 respectively). keywords: predicting factors; insomnia; patients with heart failure