A significant aspect of sleep related studies is formed by the studies that evaluate sufficient sleep duration and the impact of short or long sleep time on health. The determinants of sleep duration that are important for the continuance of both health and daily life are an important discussion area. This study was performed in order to determine the factors related to the sleep duration of individuals aged 18-65, their cultural beliefs related to sleep duration and other variables in this type of descriptive cross-sectional (n = 534). The data were collected through a three-part questionnaire consisting of 44 questions created by the researchers by searching literature. A backward multiple regression analysis was used to identify the determinants of the sleep duration. Being male, (β = -0.11), talking during sleep (β = -0.08), having problems falling asleep (β = -0.08), having the habit of setting the alarm clock (β = -0.13), and having the belief that "The time passed while sleeping is a waste, so the sleep time must be short" (β = -0.26), and "If I have insomnia, I wait to fall asleep without getting up" (β = -0.06) were found to negatively affect sleep duration. Agreeing with the statements; "Sleeping refreshes/clears the mind" (β = 0.22) "Sleeping early and getting up early makes people healthy" (β = 0.09) "Sleeping at noon for a short time is important" (β = 0.09) "I daydream before sleeping" (β = 0.178). "If I have insomnia, I use drugs" (β = 0.110) positively affects and increases sleep duration.