Sleep Quality and Cognitive Functions in Adults: A Cross-Sectional Study

Inclusion Criteria: * Between 18 and 35 years. * Ability and willingness to provide written informed consent. * Sufficient ability to read, understand, and communicate in Turkish, the language in which the assessments are administered. * Self-reported good general health, with no active medical or psychiatric conditions that significantly affect daily functioning. * Willingness and ability to wear a wearable sleep monitoring device continuously for five consecutive days and to comply with device usage instructions. * Ability to attend and complete a single-session cognitive assessment Exclusion Criteria: * Regular or frequent use of medications known to affect sleep or cognitive function, including sedative-hypnotics, benzodiazepines, antipsychotics, stimulants, opioids, or similar agents. * Initiation of, or dose changes in, psychotropic medications within the past four weeks. * Being under the influence of alcohol or illicit substances on the day of cognitive testing. * Engagement in night shift work or rotating shift schedules within the past one month. * Travel across time zones resulting in a time difference of two hours or more within the past two weeks. * Uncontrolled high daily intake of caffeine (e.g., \>400 mg/day) and unwillingness to reduce consumption during the study period. * Color blindness or other color vision deficiencies, due to their potential impact on Stroop Test performance. * Dermatological conditions, allergies, or skin lesions at the wrist that prevent wearing the device, or refusal to wear the device as required. * Acute illness within the past two weeks, including febrile infections, severe pain, or other acute medical conditions that may temporarily affect sleep or cognitive performance. * Pregnancy or early postpartum period.