Joint hypermobility is a clinical condition characterized by joints having a range of motion beyond their normal limits. Hormonal factors are thought to play a role in the development of joint hypermobility. One of the most significant indicators of prenatal androgen exposure is considered the ratio of the lengths of the second and fourth fingers (2D:4D). The 2D:4D digit ratio refers to the ratio of the lengths of the second finger (2D; index digit ) and the fourth finger (4D; ring digit). Evidence suggests that the 2D:4D ratio is developmentally stable and stabilizes from the second trimester of pregnancy onward. To our knowledge, intrauterine androgen exposure (2D:4D) has not been examined in populations with joint hypermobility. Furthermore, there are no studies investigating the relationship between this ratio and sleep quality. Therefore, the planned study aimed to examine the 2D:4D digit ratio in young adults with joint hypermobility and compare it with that of individuals without joint hypermobility. Additionally, we aimed to evaluate the relationship between 2D:4D finger ratio and sleep characteristics in young adults.