PP65 Simplifying the measurement of sleep quality: latent variable analysis of seven conceptual sleep criteria -conference paper abstract-

Publication type

Journal Article

Published in

Journal of Epidemiology and Community Health


A.A. Alghamdi, E.M. Scott, G.R. Law and G.T.H. Ellison

Publication date


In epidemiological surveys, sleep quality is assessed using seven
distinct criteria namely: sleep duration; latency; disturbance;
coughing/snoring; perceived quality;
medication and daytime sleepiness. Due to the complex functional,
conceptual and mathematical
interrelationships between these
seven criteria epidemiologists face substantial challenges assessing
which and whether/how
best to combine two or more
criteria. The aim of the present analyses was therefore to assess
whether it is possible to reduce
the number of sleep criteria used to
provide a simpler indication of ‘overall sleep quality’.

Self-reported sleep data,based on responses to seven items in the first
wave adult self-completion questionnaire of the UK’s
Understanding Society (Usoc)
longitudinal study, were analysed using exploratory factor analysis
(EFA) which was built based
on polychromic correlation matrix of
the seven sleep criteria. A value of 0.4 was chosen as the minimum
acceptable loading
factor to include in the ‘overall
sleep quality’ model. The model was tested using confirmatory factor
analysis (CFA) with
an asymptomatically
distribution-free estimation (ADF) as the chosen method of estimation.

When ‘overall sleep quality’ was considered as one continuous variable,
most of its variance was explained by just four of
sleep criteria: duration, latency,
disturbance and perceived quality, for which the EFA loading factors
were: 0.430; 0.685;
0.702; and 0.890, respectively. The
associated CFA regression standardised beta coefficients were; -0.237
(SE=0.005; p < 0.001)
for duration; 0.791 (SE=0.0195; p
< 0.001) for latency and 0.760 (SE=0.195; p < 0.001) for perceived
quality. The model fitting
indices being: root mean squared
error of approximation < 0.001; comparative fit index = 1.00; and
Tucker-Lewis index = 1.00.

Amongst adult Usoc participants (a sample that is broadly
representative of the UK population), variation in ‘overall sleep
quality’ is principally captured by
just four of sleep criteria measured in its first wave questionnaire:
sleep latency; sleep
disturbance; and perceived sleep
quality, while sleep duration plays an important role in predicting
participants’ individual
subjective assessments of sleep
quality. These four of Pittsburgh Sleep Quality Index’s seven key
subscores, are likely to
provide an adequate marker of
‘overall sleep quality’ for use in epidemiological analyses,
particularly those in which sleep
is considered rather than an
exposure or outcome of interest.








Statistical Analysis, Medicine and Health


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