Background
Sleep disorders and insomnia are prevalent worldwide, with negative health outcomes. The Pittsburgh Sleep Quality Index (PSQI) is a widely used self-report assessment tool for evaluating sleep quality, comprising seven subdomains. The Korean version of the PSQI (PSQI-K) has been tested for reliability and validity in small sample sizes but lacks large-scale validation using objective measures.
Methods
This study was conducted with 268 Korean adults attending health check programs. Participants completed the PSQI-K questionnaire and wore Fitbit devices (Fitbit Inc., USA) to ascertain sleep parameters. Reliability was analyzed using the Cronbach’s α coefficient, and construct validity was determined through factor analysis. Criteria validity was assessed by correlating their index scores with Fitbit sleep parameters. We identified the optimal cutoff for detecting sleep disorders.
Results
The Cronbach’s α coefficient was 0.61, indicating adequate internal consistency. Factor analysis revealed three factors, explaining 48.2% of sleep quality variance. The index scores were negatively correlated with Fitbit sleep efficiency, total sleep time, and number of awakenings (P<0.05). The optimal cutoff point for identifying sleep disorder groups was ≥6.
Conclusion
The PSQI-K demonstrated good reliability and validity when correlated with Fitbit sleep parameters, offering a practical screening tool for identifying sleep disorders among Korean adults. Cutoff scores can help identify patients for sleep interventions. However, further large-scale studies are required to validate these findings.

Citations

• Association of smoking cessation duration and e-cigarette switching with mental health: A cross-sectional study in Korea
  Soonsu Shin, Jae-Hong Ryoo
  Journal of Affective Disorders.2026; 397: 121029.     CrossRef
• Factor analysis on the Pittsburgh Sleep Quality Index and the Chalder Fatigue Scale sample of critical care nurses in Saudi Arabia
  Rana Ali Alameri
  Nutrition and Health.2026;[Epub]     CrossRef
• Sleep Quality Disparities by Urban-Rural Status and Housing Type among the Korean Older Adults
  Soo Jung Choi, In Cheol Hwang, Yoo Jeong Lee, Hong Yup Ahn
  Korean Journal of Geriatrics & Gerontology.2026; 27(1): 37.     CrossRef
• Factors associated with sleep quality and mental health outcomes: A sex and age-specific interaction analysis
  TaeKyun Won, Young-Joo Won
  Korean Journal of Health Education and Promotion.2026; 43(1): 71.     CrossRef
• A Theory‐Based Nursing Scale for Measuring the Impact of Sleep Disturbance on Quality of Life
  Güzel Nur Yildiz, Arzu Karakaya, Nuray Şimşek, Bahar Çiftçi
  Nursing Open.2026;[Epub]     CrossRef
• Association of work ability with job burnout and sleep quality among biosafety laboratory personnel in Xinjiang, China: a cross-sectional study
  Keke Ju, Ruikai Wu, Jing Yu, Lei Ding, Mengjie Xia, Jiwen Liu, Yaoqin Lu
  Frontiers in Public Health.2025;[Epub]     CrossRef
• Validation of the Korean version of the Sleep Hygiene Practice Scale in a Non-Clinical Population
  Dongyeop Kim, Ji Young Yun, Hye Ah Lee, Pamela Song, Heeyoung Ahn, Chien-Ming Yang, Jee Hyun Kim
  Behavioral Sleep Medicine.2024; 22(6): 791.     CrossRef
• The relationship between sleep quality and happiness among preclinical students in a medical school
  Rusdiah Ruzanna Jusoh, Kavimitha G Krishnasamy, Saila Dharishinee Alagu, Pretha Mohan, Jeslyn Tan Guan Qian, Elayevenee Elanthevan, Muhammad Zulfiqah Sadikan, Haryati Ahmad Hairi
  Journal of Education Technology in Health Sciences.2024; 11(3): 92.     CrossRef