Sleep beliefs and attitudes and the association with insomnia among psychiatric outpatients

Figures & data

Table 1. Sociodemographic and clinical characteristics of sample (n = 400).

	n	%
Age group
21–39	220	55.0
40–65	180	45.0
Gender
Male	210	52.5
Female	190	47.5
Ethnicity
Malay	105	26.3
Indian and Others	144	36.0
Chinese	151	37.8
Educational attainment
Primary or below	28	7.0
Secondary	154	38.5
Post-secondary to pre-university	164	41.0
Tertiary and above	54	13.5
Employment status
Employed	219	54.8
Economically inactive	28	7.0
Unemployed	152	38.0
Diagnosis
Schizophrenia spectrum disorder	120	30.0
Mood disorder	180	45.0
Anxiety disorder	100	25.0
Duration of illness
<2 years	61	15.3
2–5 years	76	19.0
>5 years	263	65.8
Any psychiatric comorbidity
Yes	188	46.8
No	212	53.3
Any other chronic medical condition
Yes	236	59.0
No	164	41.0
Sleep medication
Yes	140	35.0
No	260	65.0

Table 2. Adjusted β estimates of sociodemographic and clinical variables associated with DBAS total scores (n = 400).

	B	95% CI^a	p
Age group
21–39	0.263	[−0.155, 0.681]	0.217
40–65	Ref.
Gender
Male	0.071	[−0.155, 0.681]	0.709
Female	Ref
Ethnicity
Malay	−0.462	[−0.939, 0.015]	0.058
Indian and Others	−0.460	[−0.891, −0.030]	0.036
Chinese	Ref
Educational attainment
Primary or below	0.901	[0.007, 1.795]	0.048
Secondary	0.505	[−0.094, 1.103]	0.098
Post-secondary to pre-university	0.180	[−0.406, 0.767]	0.546
Tertiary and above	Ref
Employment status
Employed	0.107	[−0.293, 0.506]	0.599
Economically inactive	−0.172	[−0.940, 0.597]	0.661
Unemployed	Ref
Diagnosis
Schizophrenia spectrum disorder	0.111	[−0.419, 0.641]	0.680
Mood disorder	0.455	[−0.013, 0.924]	0.057
Anxiety disorder	Ref
Duration of illness
<2 years	Ref
2–5 years	−0.089	[−0.730, 0.553]	0.786
>5 years	−0.250	[−0.808, 0.307]	0.378
Any psychiatric comorbidity
Yes	0.569	[0.188, 0.950]	0.004
No	Ref
Any other chronic medical condition
Yes	−0.211	[−0.593, 0.171]	0.278
No	Ref
Sleep medication
Yes	0.493	[0.098, 0.887]	0.014
No	Ref

^aThe confidence interval (CI) indicates the interval which one can be 95% confident that the true β lies in that interval.

Table 3. Unadjusted and adjusted odds ratios (OR) representing results of the logistic regression to examine the associations between insomnia and DBAS scores (n = 400).

	Consequences		Worry and helplessness		Expectations		Medications		DBAS total
	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI	OR	95% CI
Unadjusted model	1.419**	[1.274, 1.581]	1.564**	[1.383, 1.768]	1.039	[0.951, 1.135]	1.194**	[1.105, 1.290]	1.595**	[1.393, 1.826]
Model 1^a	1.433**	[1.280, 1.605]	1.601**	[1.407, 1.821]	1.042	[0.950, 1.143]	1.209**	[1.115, 1.311]	1.627**	[1.411, 1.876]
Model 2^b	1.429**	[1.262, 1.619]	1.587**	[1.381, 1.824]	1.072	[0.966, 1.189]	1.161*	[1.062, 1.270]	1.599**	[1.372, 1.863]

CI = confidence interval. The confidence interval indicates the interval which one can be 95% confident that the true OR lies in that interval.

Statistically significant results are in bold; *p < 0.01. **p < 0.001.

^aAdjusted for sociodemographic variables (i.e. age group, gender, ethnicity, educational attainment, and employment status).

^bAdjusted for sociodemographic variables and clinical variables (i.e. diagnosis, duration of illness, presence of psychiatric comorbidity, presence of chronic physical condition, and use of sleep medication).

Table 4. Adjusted odd ratios representing the association between insomnia and sleep beliefs within each diagnostic group.

	Mood disorders (n = 180)			Schizophrenia spectrum disorders (n = 120)			Anxiety disorders (n = 100)
	OR	p	95% CI	OR	p	95% CI	OR	p	95% CI
Consequences	1.456	<0.001	[1.198, 1.769]	1.721	<0.001	[1.269, 2.334]	1.201	0.217	[0.898, 1.605]
Worry and helplessness	1.707	<0.001	[1.361, 2.140]	1.765	<0.001	[1.305, 2.387]	1.342	0.091	[0.954, 1.887]
Medications	1.211	0.007	[1.055, 1.390]	1.093	0.411	[0.884, 1.351]	1.032	0.770	[0.833, 1.279]
DBAS total	1.647	<0.001	[1.305, 2.080]	1.960	0.001	[1.341, 2.864]	1.243	0.248	[0.859, 1.798]

Multivariable logistic regression with DBAS scores as independent variables and insomnia status as outcome variable, controlling for sociodemographic and clinical variables. Statistically significant results are in bold.