A Survey of Sleep Quality in Patients With 13 Types of Mental Disorders

A Survey of Sleep Quality in Patients With 13 Types of Mental Disorders

Cui Lijun, MD; Li Ke-qing, PhD; Sun Xiuli, MD; Cui Ze, MD; Jiang Qinpu, MD; Han Yanchao, MD; Gao Lianghui, MD; Zhang Yang, MD; Li Jianfeng, MD; Liu Yongqiao, MD; Yang Laohu, MD; and Lv Hua, MD

A sleep disorder (somnipathy) is a disruption of a person’s sleep patterns. International epidemiology studies showed that the rate of sleep quality disorder was 15% to 35% in adults.1,2 Some sleep disorders are serious enough to interfere with normal physical, mental, and emotional functioning. However, the effects of mental disorders on the sleeping period and rhythm have been less reported. In this study, we investigated the sleep characteristics of a community sample of patients with 13 common types of mental disorders in Hebei Province, Baoding, China.

METHOD

Subjects

All of the participants were sampled from the Epidemiologic Sites Survey of Mental Illness conducted from October 2004 to March 2005 at the Mental Health Center of Hebei Province. The sample included 24,000 individuals, 20,716 of whom completed the survey. In addition to the 13 types of mental disorders, this survey also measured physical illness associated with mental disorders, unspecified anxiety disorder, unspecified depressive disorder, mental retardation, senile dementia, and other diseases that were not included in the study group.

The study group included 1,874 subjects aged 18-86 (mean ± SD = 47±13) years with 13 common types of mental disorders according to the Structured Clinical Interview for DSM-IV-TR Axis I Disorders-Patient Edition. Of those, 899 were male and 975 were female, with an education level of 0-17 (mean ± SD = 6 ± 4) years. Marital status included single (n = 122), married (n = 1,506), remarried (n = 45), separated or divorced (n = 44), and widowed (n = 157). Subjects reported living alone (n = 134), living in a dormitory (n = 14), and living with family (n = 1,726). Professional status included farmer/fisher (n = 1,367), worker/servicer (n = 79), professional technician/administrative staff (n = 57), self-employed/contractor (n = 150), retiree (n = 51), unemployed (n = 55), student (n = 5), housewife (n = 109), and other (n = 1).

The 13 types of mental disorders included major depressive disorder (n = 399), panic disorder (n = 55), generalized anxiety disorder (n = 127), posttraumatic stress disorder (PTSD; n = 66), dysthymic disorder (n = 411), bipolar affective disorder (n = 36), somatoform disorder (n = 106), obsessive-compulsive disorder (n = 29), specific phobia (n = 139), schizophrenia (n = 106), adjustment disorder (n = 26), social phobia (n = 32), and alcohol abuse and dependence (n = 342).

The control group comprised 15,117 subjects with no mental disorders according to the survey and included 7,514 females and 7,603 males, with a mean ± SD age of 43 ± 15 years.

This study was censored and permitted by the Hospital Ethics Committee of the Mental Health Center of Hebei Province. The respondents or their guardian signed the informed consents.

The Evaluation of Sleep Quality

The revised Chinese edition of the Pittsburgh Sleep Quality Index (PSQI)4 was used to evaluate the sleep quality of the respondents in the last month. The PSQI is composed of 19 self-rated questions and 5 questions rated by others. Only the self-rated items are included in the test scores (18 questions, as the 19th self-rated item is not scored) and are divided into 7 categories inquiring about subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medications, and daytime dysfunction. Each item score ranges from 0 (no difficulty) to 3 (severe difficulty). The component scores are summed to produce a global score that ranges from 0-21, and a higher global score indicates worse sleep quality. A PSQI global score is the standard used to evaluate sleep quality. A PSQI global score > 7 is considered to be suggestive of significant sleep disturbance, and a PSQI global score ≤ 7 is considered to be qualified sleep. The scale was administered by psychiatrists and nurses who asked respondents each survey item.

The Evaluation of Social Life Function

The evaluation of social life function was conducted by psychiatrists with the Global Assessment of Functioning (GAF),3 which scores in the range of 1-100. A higher GAF score indicates good functioning. The application of the scale achieved good homogeneity after training, with the mean κ value above 0.85.

• There is a high prevalence of sleep disorders in patients with mental disorders.
• Longer sleep latency and shorter sleep duration were the most common characteristics of low quality sleep in patients with mental disorders and were most notable in those with depression.

Statistical Analysis

All data were input into SPSS 11.0 (SPSS Inc, Chicago, Illinois) for analysis. Subjects with mental disorders with sleep disturbance were compared with the control respondents. The measurement data were analyzed via applied t test. Due to nonnormal distribution of data, nonparametric Mann-Whitney U was used to analyze sleep latency and sleep duration among study and control subjects, χ2 test was used to compare general data, and exact probability was applied to analyze the existence of sleep disturbance among different subtypes of schizophrenia.

RESULTS

Comparison of the Incidence Rate of Sleep Disturbances

Of 20,716 survey respondents, 2,411 were found to have a sleep disorder as assessed by the PSQI (11.64%). The incidence rate of sleep disturbance was 48.61% (n = 911) in the study group, which was higher than the rate in the control group (5.55%, n = 839; P < .01). The comparison of sleep quality between the study group and the control group is shown in Table 1.

Table 1 indicates that the total PSQI scores of the patients with mental disorders were higher than those of the control group (P < .01-.05), and the patients with major depressive disorder, panic disorder, and generalized anxiety disorder had the highest scores. The patients with major depressive disorder, generalized anxiety disorder, panic disorder, PTSD, dysthymic disorder, somatoform disorder, and bipolar affective disorder had higher scores on the incidence rate of sleep disturbances than the control group (P < .01). The proportion of patients taking hypnotic drugs was highest for patients with schizophrenia and lowest for those with social phobia or alcohol abuse and dependence. The daytime function of the patients with major depressive disorder was the lowest of all groups.

Comparison of Sleep Characteristics

Table 2 shows that the control group fell asleep within 10 minutes after going to bed and woke up at 6:30 am, and the actual sleep duration was 8 hours. However, the patients with mental disorders had different sleep characteristics compared to the control group. Their time to fall asleep (50 ± 60 minutes) was longer (P < .01) than the control group. The patients with major depressive; disorder or panic disorder had a delayed time to fall asleep the patients with major depressive disorder, generalized anxiety disorder, or dysthymic disorder had the earlier wakeup time (P < .01~.05); and the actual sleep duration was shorter among the patients with major depressive disorder or PTSD (P < .01). Difficulty falling asleep, earlier wakeup time, and shorter sleep duration were characteristic of major depressive disorder according to our findings.

Comparison of Characteristics of Subjects With Mental Disorders and Sleep Problems

Tables 3 and 4 indicate that those patients with mental disorders who were older; who had lower education levels, lower incomes, and fewer family members; who were farmers, retired, or students/housewives; or who were widowed had more sleep problems than other subjects with mental disorders. The patients with undifferentiated type schizophrenia had fewer sleep disorders (P < .01); however, there was no relation between the severity of depression and sleep disorders.

DISCUSSION

In this study, the incidence rate of sleep disorders was 11.6% in a community group, which resembles the rate of 10.8% reported by Yawen et al.4 The rate of sleep disturbance in the control group was 5.55%, and the rate of 13 types of mental disorders was 19.30%-69.2%, with a mean incidence rate of 48.6%, which is similar to the results of Roth et al5 (47.8%-53.7%) and Chuanyuan et al (41.86%).6

Mental disorders play an important role in sleep problems within the community, and major depressive disorder (69.92%) and generalized anxiety disorder (58.27%) were common among these mental disorders in our study but were lower than the result (80%) reported by Armitage.7 The sleep problems of the patients with the 13 common types of mental disorders had similar characteristics, such as difficulty falling asleep and shorter duration of sleep; moreover, patients with major depressive disorder (P < .01), dysthymic disorder (P < .01), and generalized anxiety disorder (P < .05) experienced early awakening. This study showed that sleep quality problems were higher in patients with mental disorders who were female, older, less educated, retired or farmers or students/housewives, and widowed, similar to the results of Rocha et al.8

This study indicates that there were disturbances in sleep quality in the patients with anxiety disorder, which involved longer sleep latency and shorter actual sleep duration. Moreover, the patients with social phobia, whose sleep disturbance rate was 28.12%, had lower daytime function than healthy controls. Buckner et al9 reported that social anxiety was positively correlated with syndromes of insomnia, especially with sleep dissatisfaction, sleep-related functional impairment, perception of a sleep problem to others, and distress about sleep problems. So, our findings support the hypothesis that social anxiety is related to sleep quality. The rate of patients with PTSD with sleep disturbance was 53.03%, and all of the factors of the PSQI showed that the patients with PTSD had distinct sleep quality disturbance. However, sleep problems are a common symptom of patients with PTSD.

The present study showed that the time to fall asleep was 60 minutes on average in patients with major depressive disorder; furthermore, the patients with major depressive disorder were waking up earlier and had weaker daily function than the control population. However, sleep quality was not significantly correlated with severity of depression, which indicates that sleep problems might emerge in early periods of depression. So, our findings suggest that the sleep problems had a marked relationship with depression and anxiety disorders. Problems of sleep quality might increase the risk of depression and anxiety, and symptoms of a sleeping problem might be one of the symptoms of depression, which resembles the findings of studies both domestic and abroad.11-14

The incidence rate of sleep problems was 43.40% in patients with schizophrenia. Shorter sleeping time and a higher score on the neuroleptic drugs factor of the PSQI indicate that neuroleptics might keep these patients’ sleeping time normal; however, the time to fall asleep was longer than that of the control population. In addition, sleeping problems seldom happen in the undifferentiated subtype; however, there were differences among the other subtypes of schizophrenia, with paranoid ranking first (67.39%), residual ranking second (19.57%), and disorganized ranking third (13.04%).

A limitation to this study is that sleep duration and sleep latency on the PSQI were subjectively assessed by patients. The scores were affected by the patient’s emotional impact, so there were some deviations between the patient’s actual situation and score. But, because of the large sample size and a variety of common mental disorders quantitatively assessed by the SCID and PSQI and good consistency among the raters, the results were reliable.

Author affiliations: Health Center of Hebei Province, Hebei Province, Baoding, China.

Potential conflicts of interest: None reported.

Funding/support: None reported.

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