Sleep Disturbance and Depressive Tendency in Bed Partners of Patients With Obstructive Sleep Apnea

Snoring, apnea, and arousal are commonly observed during sleep in patients with obstructive sleep apnea (OSA), and these nocturnal symptoms frequently disturb their bed partners. We aimed to evaluate the sleep disturbance and depressive tendency in the bed partners of patients with OSA. A cross-sectional, prospective study was conducted. A total of 136 patients with OSA and their bed partners were recruited. We analyzed the demographic data of both patients with OSA and bed partners and the polysomnography parameters of patients with OSA. The sleep quality of bed partners was assessed using the Chinese version of the Pittsburgh Sleep Quality Index (PSQI), and depressive symptoms were evaluated using the Center for Epidemiologic Studies Depression Scale (CES-D). The mean apnea– hypopnea index (AHI) was 43.5/h among all participants (76.5% male). Among bed partners, the mean PSQI score was 7.8 and the mean CES-D score was 15.4. The prevalence of chronic disease was signicantly higher in bed partners with sleep disturbance (PSQI > 5) and depressive tendency (CES-D ≥ 16). The AHI and snore index of patients with OSA were not associated with bed partners’ sleep disturbance and depressive tendency, which were stratied according to PSQI (> 5 and ≤ 5) and CES-D ( ≥ 16 and < 16), respectively. The CES-D score was positively correlated with the PSQI score in the bed partners of patients with OSA (r = 0.426, p < 0.001). Bed partners tended to have sleep disturbance, which was unrelated to the severity of AHI and snoring in patients with OSA. Poor sleep quality may cause depressive tendency and chronic disease in the bed partners of patients with OSA.


Introduction
In the third edition of the International Classi cation of Sleep Disorders (ICSD-3), obstructive sleep apnea (OSA) is de ned as a clinical syndrome characterized by the repetitive collapse of the upper airway, causing episodes of partial or complete airway obstructions during sleep. These obstructions decrease blood oxygen saturation and are usually terminated by arousal from sleep 1 . OSA is an extremely common sleep disorder; its estimated prevalence ranges from 9-38% in the adult population 2 . Untreated OSA is associated with long-term health consequences, including cardiovascular disease, stroke, metabolic disorders, cognitive dysfunction, and increased risk of accidents 3,4 . In addition, OSA not only affects patients' health but also in uences their families. As the body attempts to restore the patency of the upper airway, patients experience recurrent arousals from sleep. Periodic leg movement in sleep (PLMS) is also common among patients with OSA 5 . Nocturnal symptoms, including loud snoring, apnea, restless sleep, and leg movement, mostly go unnoticed among patients with OSA but disturb the sleep of their bed partners.
Most research examining the in uence of OSA on bed partners has found that OSA negatively affects sleep quality and quality of life 6 . In a cross-sectional study, 55% of the bed partners of 37 patients suspected of having OSA experienced decreased sleep quality due to snoring 7 . A study of 46 bed partners of patients with moderate to severe OSA observed that 66% of participants reported poor sleep quality 8 .
Studies using polysomnography (PSG) to assess the sleep quality of the bed partners of patients with OSA have recorded signi cant sleep disturbance [9][10][11] . However, the causal association between nocturnal symptoms in patients with OSA and impaired sleep of their bed partners remains controversial.
Additionally, OSA interferes with patients' interpersonal relationships with their bed partners. A prospective study discovered that wives of men with apnea were 2.9 times more likely to sleep apart from their partner relative to their group composed of wives whose husbands did not have apnea 12 . In an early study, decreased marital satisfaction was reported by wives of OSA patients 13 . Sleep disruption of the bed partners from sleep apnea resulted in frustration and strained relationships 14 15 . These ndings support the hypothesis that OSA has broader effects on the mental health of the bed partners.
The aim of this study was to evaluate sleep disturbance by using the PSQI score and depressive tendency by using the CES-D score recorded by the bed partners of patients with OSA. We investigated the effect of nocturnal symptoms from OSA on the subjective sleep quality of bed partners. In addition, the relationship between sleep disturbance and depressive tendency of bed partners was assessed.

Participants
A consecutive series of patients who had sleep-disordered breathing and the presence of a bed partner for more than a month were prospectively recruited from a medical center and a regional teaching hospital in Northern Taiwan between December 2010 and October 2012. Patients were referred for an in-laboratory PSG. The exclusion criteria were age < 18 years and an apnea-hypopnea index (AHI) < 5. This study was approved by the Institutional Review Board of Chang Gung Memorial Hospital (99-3059B, 100-3664C), and informed consent was obtained from each participant and their bed partner. Patient con dentiality was maintained as no patients' identi ers were collected and the private will be carefully protected. All research process was in accordance with the Declaration of Helsinki.

Questionnaires
Each participant completed a questionnaire that inquired into their age, sex, marital status, and educational level and contained questions based on the Epworth Sleepiness Scale (ESS) 16 . The body mass index (BMI) and neck circumference of all participants were recorded. Bed partners were asked to complete a questionnaire that inquired into their age, sex, educational level, and chronic disease status, including that of cerebrovascular disease, cardiovascular disease, diabetes mellitus, cancer, and chronic lung disease.
The Pittsburgh Sleep Quality Index (PSQI) is the most commonly used self-rated questionnaire for evaluating subjective sleep quality. The PSQI comprises 19 individual items, and the sum of the component scores yields a PSQI global score of sleep quality, which ranges from 0 to 21. When a cut-off score of > 5 was used, the PSQI reportedly had a sensitivity of 89.6% and a speci city of 86.5% in identifying cases of sleep disorders 17 . The Chinese version of the PSQI is also a reliable and valid tool for assessing sleep quality 18 . The sleep quality of bed partners was assessed using the Chinese version of the PSQI, and a cut-off score of > 5 was used to identify sleep disturbance.
The Center for Epidemiologic Studies Depression Scale (CES-D) is a commonly used questionnaire for evaluating the level of depressive symptoms. The CES-D is a 20-item self-report questionnaire with total scores ranging from 0 to 60. Higher scores indicate more severe depressive symptoms and scores ≥ 16 indicate depressive tendency 19 . The CES-D has been translated into Chinese and used to screen for depressive disorders 20,21 . Depressive symptoms were assessed using the CES-D, and a cut-off score of ≥ 16 indicated a clinically signi cant level of depressive symptoms. The questionnaires for the bed partner were given to the patient from the sleep laboratory, and they were asked to return the completed questionnaires by mail.

Polysomnography
Standard overnight PSG was performed using a computerized PSG system (N7000 Embla, Broom eld, USA). We measured the following: electroencephalogram (EEG), bilateral electrooculogram (EOG), submental and bilateral anterior tibialis electromyogram (EMG), and electrocardiogram (ECG) parameters and nasal and oronasal air ow (using a thermistor and indicated using nasal pressure), arterial oxygen saturation (through nger probe pulse oximetry), chest and abdominal movements (through inductance plethysmography), and body position. Snoring was measured using a vibration sensor placed on the carotid triangle on the neck. Sleep stages were manually scored in 30-s epochs by using the American Academy of Sleep Medicine (AASM) scoring criteria 22 .
Obstructive apnea was de ned as the absence of air ow for at least 10 s in the presence of respiratory effort, whereas central apnea was de ned as the absence of air ow without concurrent respiratory effort. Hypopnea was considered to have occurred when a > 50% decrease in air ow occurred for over 10 s followed by at least 3% oxygen desaturation or EEG arousal 22 . AHI was de ned as the average number of apneas and hypopneas per hour of sleep. The snore index was de ned as the number of snore events per hour of sleep. Leg movement (LM) was de ned as an 8-µV increase in the EMG voltage of the right and left anterior tibialis above the resting EMG voltage, lasting 0.5-10 s. LMs occurring in a wide time window extending from 0.5 s before the start of a respiratory event (apnea or hypopnea) to 0.5 s after its end were not counted. Periodic leg movement (PLM) was de ned as a minimum of four consecutive LM events with a 5-90-s interval during sleep. The PLM index (PLMI) was scored as the number of PLM per hour of total sleep time 23 .

Statistical analysis
Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) for Windows (version 19.0; SPSS Inc., Chicago, IL, USA). The characteristics of patients and bed partners are presented as the mean ± standard deviation for continuous variables and as frequency (percentage) for categorical variables. The sleep disturbance of bed partners was strati ed according to PSQI score (> 5 and ≤ 5), and the depressive tendency of bed partners was strati ed according to the CES-D score (≥ 16 and < 16). Differences in continuous variables were analyzed using the t test and Mann-Whitney U test. Differences in categorical variables were analyzed using the chi-square test. The variables associated with sleep disturbance and depressive tendency of bed partners were evaluated through multivariable logistic regression at the thresholds of PSQI score > 5 and CES-D score ≥ 16, respectively. Pearson correlation analysis was performed to quantify the degree of relationship between sleep quality, as determined through the PSQI score, and depressive symptoms, as determined through the CES-D score, among bed partners. A p value of < 0.05 was considered statistically signi cant.

Participant characteristics
Fourteen patients aged < 18 years or with an AHI of < 5 were excluded. A total of 136 patients and their bed partners were included in this study. The following characteristics and PSG ndings of patients are listed in Table 1: age, sex, BMI, marital status, educational level, ESS score, AHI, snore index, and PLMI. The mean age of patients was 50.6 years, with the majority being male patients (76.5%). The mean BMI was 26.7 kg/m 2 . PSG ndings revealed that patients had a mean AHI of 43.5/h and a mean snore index of 147.0/h. The characteristics, sleep quality, and depressive symptoms of bed partners are listed in Table 2. The mean age of bed partners was 49.1 years, and 41.9% of them had chronic disease. The average PSQI score, indicating sleep quality, was 7.8, and the average CES-D score, indicating depressive symptoms, was 15.4. Data are presented as means ± standard deviation or number (%).

Discussion
This study had a sample of 136 patients with OSA, and their bed partners were more likely to report sleep disturbance. Nevertheless, the frequency of apnea-hypopnea and snoring resulting from OSA did not negatively affect the sleep quality of bed partners. Self-reported depressive symptom scores and the prevalence of chronic disease were higher in bed partners with sleep disturbance. Additionally, bed partner-reported depressive symptoms were positively associated with sleep disturbance. Our study had some limitations. First, the majority of the bed partners were female, and this may have independently in uenced the higher incidence of both sleep disturbance and depressive symptoms. Second, we did not apply the PSG to the bed partners, and it was unclear whether the bed partners had OSA. Sleep disturbance may have been caused by bed partners' own OSA, and this may have in uenced the results. Third, we investigated sleep disturbance and depressive tendency in the bed partners of patients with OSA by using only one type of questionnaire, which may not have been sensitive to some of the feelings experienced by bed partners. Further research should incorporate more questionnaires for assessing sleep quality and depressive symptoms. Fourth, the self-reported data may have been affected by recall bias, especially considering that individuals with depression tend to remember and report more negative things. This bias may have led to an overestimation of the relative risk involved with various factors and thereby in uenced the results.
In conclusion, sleep disturbance is often a shared experience for the bed partners of patients with OSA. However, the night symptoms from OSA, including the severity of AHI, snoring, and PLMS, may not affect partner-assessed sleep. Depression and chronic disease are associated with the sleep disturbance of bed partners, but their causal relationship is unknown. Additional studies are warranted to recognize the causes of poor sleep quality and the effects of OSA on bed partners. Figure 1 Pearson correlation analysis was performed to quantify the extent of the relationship between sleep quality, as determined through the PSQI score, and depressive symptoms, as determined through the CES-D score, in bed partners. A positive linear correlation (r = 0.426, p < 0.001) was found. PSQI: Pittsburgh Sleep Quality Index, CES-D: Center for Epidemiological Studies Depression Scale.