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Insomnia Severity Index (ISI)

Title of the Portuguese Version

Índice de Gravidade da Insónia

Original Version

Morin C. (1993)

Portuguese Version

Clemente, V. (2013, 2017)

General Description

The ISI is one of the most known scales on insomnia which evaluates the severity of insomnia complaints. It is composed of 7 items addressing the main nighttime and daytime insomnia symptoms (difficulty falling asleep, sleep maintenance difficulty, waking up too early, (dis)satisfaction with sleep, interference with daily functioning, noticeable impairment due to sleep problems, and concern about sleep problems). Each item is rated on a 5-point Likert scale, yielding a total score ranging from 0 to 28, interpreted as follows: no clinical insomnia (0-7); sub-threshold insomnia (8-14); moderate insomnia (15-21); and severe insomnia (22-28).

  • Clemente, V., Allen Gomes, A., Mendes, M. M., Marques, D. R., Russo, B., Serra, J., Moutinho dos Santos, J., & Moita., J. (2017). The European Portuguese version of the insomnia severity index (ISI): Reliability, validity and diagnostic accuracy [Abstract]. Sleep Medicine, 40, e67. doi:10.1016/j.sleep.2017.11.191 http://hdl.handle.net/10316/47386


  • Clemente, V., Ruivo Marques, D., Miller-Mendes, M., Morin, C. M., Serra, J., & Allen Gomes, A. (2021). The European Portuguese version of the insomnia severity index. Journal of Sleep Research, 30(1), e13198.  https://doi.org/10.1111/jsr.13198


  • Morin C. (1993). Insomnia: Psychological assessment and management. New York: The Guilford Press.


Vanda Clemente – vandaclem@gmail.com