Psychometric properties of a subjective sleep quality index to be used with the elderly: an exploratory study

Abstract

Objectives: Explore the psychometric properties of a sleep quality index to be used with the elderly population. Methods: 99 elderly (mean age, M=78.65; SD= 6.92; range=60-95) under social responses in institutions from Coimbra Council were assessed through a sleep questionnaire, composed of a sleep quality index and questions assessing sleep correlates. The sleep index is composed by seven items assessing sleep latency, difficulty in falling asleep, number of night awakenings, waking up spontaneously too early, subjective perception that waking up too early constitutes a problem for the person and two items that evaluate general subjective sleep quality and sleep depth. Results: KMO = .830; Bartlett’s Test of Sphericity ≤.001. A principal components analysis and the scree plot inspection revealed a one-factor solution, explaining 48.8% of the total variance. Very good internal consistency (Cronbach alpha coefficient; α=.812). Conclusion: This sleep quality index presents good psychometric properties. Since, in terms of assessment, it is important not to overload the elderly population, this very short instrument constitutes a good option to assess sleep quality.