Sick and Tired: Understanding and Managing Sleep Difficulties in ...

efficiency, suggesting that participants were spending large periods of time in bed while
not asleep.
Fifty participants (49.50%) reported using medication (prescribed or over the counter)
to improve their sleep at least three times per week, although 41 participants (40.60%)
had not used any hypnotic medication in the past month. The levels of reported daytime
dysfunction as a result of poor sleep were high, with over half the sample (N=59,
58.4%) reporting that they experienced a problem in maintaining enthusiasm to get
things done at least three or more times a week.
To ensure the questionnaire measures contained items that were measuring the same
underlying construct within this specific population, the inter-item consistency of the
scales was analysed based on the criterion outlined in the introduction to this thesis (p.
18), and mean inter-item coefficients of between 0.2 and 0.4, which are indicative that
the items within the scale are exploring similar constructs (Piedmont & Hyland, 1993).
To check the internal reliability of the scales used within this study, Cronbach‟s alpha
and inter-item coefficients were calculated for each scale in the analysis. The
suppression of competing activities, denial and mental and behavioural disengagement
scales of the COPE, and role limitations due to physical problems subscale of the SF36,
yielded Cronbach‟s alpha scores below 0.6 or had inter-item correlation coefficients
below 0.2 or above 0.5 (Field, 2009; Piedmont & Hyland, 1993) and were therefore
excluded from further analysis. The role limitations due to physical problems scale of
the SF-36 also revealed ceiling effects (with the majority of the sample scoring 0,
indicating highly reduced quality of life) which limited its use for this sample. Median
values, interquartile ranges and Cronbach‟s alpha scores for the assessment measures
are outlined in Table 1 (p. 62).
Correlation Analysis
Spearman‟s r correlation coefficients were calculated between sleep, coping and health
related quality of life variables. Spearman‟s correlation coefficient was used as the data
were considered to be ordinal level data and to account for the non-normal distribution
of the study variables.
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