A Study on the Evaluation of Brainstem Dysfunction in Rapid Eye Movement Sleep Behavior Disorder Using Video Nystagmography

Background@#This study aimed to differentiate video nystagmography (VNG) characteristics, including the video head impulse test (vHIT), in patients with idiopathic rapid eye movement behavior disorder (RBD) from healthy controls, which is considered a precursor to degenerative diseases. @*Methods@#One hundred eighty-five patients underwent overnight polysomnography (PSG) and VNG. Based on overnight PSG, 27 patients with RBD or REM sleep without atonia (RWA) and AHI<15 were categorized into the RBD group, 34 patients with RBD/RWA and AHI≥15 were grouped into the combined group. Sixty patients with AHI≥15 and no RBD/RWA were included in the obstructive sleep apnea (OSA) group, and 64 negative participants were assigned to the control group. In VNG, we measured the gain of vHIT in each canal, with the latency, amplitude, and velocity of horizontal saccades and smooth pursuit. We compared the results between groups using ANOVA, after normalization and adjustment for age and sex. @*Results@#The gain of vHIT in the left horizontal canal was decreased in the RBD group, but it was more pronounced in the OSA group. Elevated gain of the left posterior canal was seen in the RBD group, but technical errors were attributable. The RBD group displayed prolonged latency of saccade on the left side and slowed saccade on the right side, but these were statistically insignificant. @*Conclusions@#The VNG study revealed differences between the sleep disorders, potentially reflecting brainstem function in each disorder. However, these differences lacked statistical significance. We anticipate that significant results could be obtained with more controlled conditions.

Evaluation of Vestibular Function in Sleep Disorders

Objectives@#The aim of this study was to evaluate dizziness in patients with sleep disorders, objectively identify vestibular function through the vestibulo-ocular reflex (VOR) using the video Head Impulse Test (vHIT), and evaluate the association between these findings. @*Methods@#Among the patients who visited the sleep clinic from June to October 2021, 69 who underwent both polysomnography (PSG) and vHIT were included. Participants completed questionnaires including the Dizziness Handicap Inventory (DHI), Beck Anxiety Inventory, Korean-Beck Depression Inventory-II, Epworth Sleepiness Scale, Insomnia Severity Index (ISI), and Pittsburgh Sleep Quality Index (PSQI). The subjects were classified into four groups: insomnia (n=4), rapid eye movement sleep behavior disorder (RBD) (n=13), obstructive sleep apnea syndrome (OSAS) (n=34), and RBD and OSAS (n=18). Moderate to severe OSAS (n=49) was compared with no OSAS and mild OSAS (n=20). @*Results@#In comparison of the four groups according to sleep disorders, the OSAS patients showed the highest DHI scores and the lowest VOR gain, but statistical significance was not found. Although all VOR gains were within the normal range, the VOR gain of the left posterior semicircular canal was significantly lower in the moderate to severe OSA group than in the no OSA and mild OSA groups (1.02±0.18 vs. 0.94±0.10, p=0.019). DHI total scores showed no correlation with VOR gain but showed a positive correlation with ISI (r=0.422, p=0.001) and PSQI (r=0.287, p=0.022). Among PSG parameters, lowest oxygen saturation (SaO2) and percentage of time with SaO2 less than 90% were correlated with the emotional score of DHI (r=-0.245, p=0.043 and r=0.311, p=0.010, respectively). @*Conclusions@#Although our study could not objectively confirm vestibular dysfunction in patients with sleep disorders, we found that subjective sleep complaints were associated with dizziness and hypoxic conditions during sleep were associated with emotional aspects of dizziness. This suggests that the treatment of concomitant sleep disorders may improve dizziness.

The Oxygen Desaturation Index for Severity Assessment of Obstructive Sleep Apnea Associated With Cigarette Smoking

Objectives@#Nicotine stimulates release of neurotransmitters that regulate the sleep-wake cycle and thereby leads to insomnia. Smoking is associated with upper airway distress; however, its role in severe sleep-related breathing disorders remains controversial. In this study, we investigated the effects of smoking on obstructive sleep apnea (OSA). @*Methods@#We investigated 1,163 patients diagnosed with OSA who underwent polysomnography between March 2020 and July 2022. We recorded details including smoking status (current, former, and non-smoker), demographics, questionnaire-related data, and polysomnography findings and performed univariate analysis to compare these variables between smokers and non-smokers. We also analyzed the correlation between smoking status and OSA severity. The risk of smoking on the severity of OSA was determined using logistic regression analysis. @*Results@#Current and former smokers included 461 male (49.1%) and 10 female (4.4%) (p=0.001). Smokers had a high apnea-hypopnea index (AHI) and oxygen desaturation index (ODI) (p15, odds ratio 1.33, p=0.04), and AHI was independent of smoking. @*Conclusions@#Controversy regarding the severity of OSA with smoking has currently not been definitively determined. However, our results provide new evidence to support the association between smoking and the ODI, which few studies have investigated to date.

A Case of Seizure Like Movement During Rapid Eye Movement Sleep Diagnosed With Pseudo-Rapid Eye Movement Sleep Behavior Disorder Associated With Severe Obstructive Sleep Apnea

Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by complex motor behaviors and REM without atonia. RBD shows diverse clinical manifestations, ranging from typical violent dreamenacting behaviors to relatively subtle limb movements. Sleep disorders such as obstructive sleep apnea (OSA) and nocturnal seizure that mimic RBD symptoms are referred to as pseudo-RBD. We describe a patient who showed an atypical clinical presentation of pseudo-RBD associated with severe OSA. Polysomnography with a full 10–20 electroencephalography montage was useful for accurate diagnosis.

Clinical Differences of Insomnia Subtype According to Actigraphy Based Objective Short Sleep, Subjective Short Sleep, and Normal Sleep

This study aims to examine the clinical differences between objective short sleep insomniacs (OSSI) and subjective short sleep insomniacs (SSSI). Methods: We enrolled 79 patients (aged 27–74 years) with chronic insomnia disorder (CID) who underwent overnight polysomnography (PSG) and completed sleep-related questionnaires as well as habitual sleep time. All of them completed actigraphy (ACT) recording for one week prior to the PSG study. Objective sleep duration for one-week average sleep was calculated by ACT, and subjective sleep duration was counted through self-reported habitual sleep time. We divided the subjects into three groups; OSSI (<6 hight), SSSI (objective sleep ≥6 hight and subjective sleep <6 h/ night), and normal sleep duration insomniacs (NSDI, subjective sleep ≥6 hight). Results: The three groups namely OSSI, SSSI, and NSDI had 25 (31.6%), 36 (45.6%), and 18 (22.8%) subjects, respectively. The SSSI were significantly older and had higher daytime sleepiness than the OSSI. According to the PSG results, the OSSI showed shorter sleep latency (11.86 min vs. 39.69 min) and N2 sleep % (59.43% vs. 67.96%), and longer rapid eye movement sleep % (20.79% vs. 15.47%) than that in the NSDI. There was no difference in treatment response between groups. Conclusions: 45.6% of CID patients underestimated their sleep relative to objective sleep. However, there were no differences in total sleep time on PSG between groups. The OSSI showed younger age and more daytime sleepiness, and the SSSI showed poorer sleep quality than the NSDI. These findings suggest that long-term ACT recording in a casual environment would be useful to monitor objective sleep in patients with CID, particularly, in subjectively short sleep insomniacs.

Comparison of Sleep, Perceived Health, and Job Stress According to Symptoms of Shift Work Disorder in Shift Nurses

This study aimed to investigate the prevalence of symptoms of shift work disorder (SSWD) and its related factors in rapidly rotating three-shift nurses. Methods: We enrolled 344 nurses (mean age, 28.7 years) without prior history of sleep disturbance before starting shift work in a university-affiliated hospital. SSWD were defined using self-reported sleep questionnaires (insomnia severity index >14 and/or Epworth Sleepiness Scale ≥10) and without any sleep problem before shift work. Sleep pattern in each of the three shifts was measured using the Munich Chronotype Questionnaire for Shift-Workers. Mood (anxiety, depression) and job stress were also measured using self-reported questionnaires. Results: Our results showed that 62.2% of the participants presented SSWD. Compared to the non-SWD group, the SSWD group showed worse sleep hygiene, lower total sleep time (TST) during workdays, higher anxiety and depressive mood, and higher job stress. In the SSWD group, the evening chronotype individuals presented the shortest TST during day shifts, while the morning chronotype individuals presented the shortest TST during evening shifts. Conclusions: SSWD is highly prevalent in fast rotating three-shift nurses. This study suggests that intensive education on sleep hygiene and appropriate scheduling of shift work while considering individual chronotypes may improve sleep patterns and sleep quality of shift workers and minimize SSWD.

Effects of Organic Light-Emitting Diodes on Circadian Rhythm and Sleep

Objective@#Organic light-emitting diodes (OLEDs) emit less blue light than traditional light-emitting diodes (LEDs), and we previously found that early-night OLED light exposure (LE) delays the melatonin phase by less than LED at a color temperature of 4,000 K. As a follow-up study, we investigated the effects of OLED and LED at a different color temperature (3,000 K) on melatonin profile, sleep, and vigilance. @*Methods@#24 healthy subjects (27.5±5.1 years) were exposed to three light conditions [OLED, LED, and dim light (DL)] from 17:30 to 24:00, in a random order and with a 1-week interval. Saliva samples for melatonin were taken every hour from 18:00 to 24:00. Polysomnography (PSG) and a psychomotor vigilance test (PVT) were performed. @*Results@#Melatonin onset time was significantly delayed under OLED and LED compared with DL, with no significant difference between OLED and LED. The mean melatonin level at 24:00 under LED was lower than that under DL, but there was no significant difference between OLED LE and DL. The percentage of slow wave sleep (N3) in LED was significantly lower than in OLED. @*Conclusion@#Exposure to light in the evening can suppress melatonin secretion late at night and disturb deep sleep, and those effects are slightly worse under LED than OLED.

Effect of Light Emitted by Smartphones at Bedtime on Circadian Rhythm and Sleep: Is It Different between Day Worker and Shift Worker?

Objectives@#Light at night (LAN) can suppress melatonin secretion and thus disturb normal sleep. The aim of this study was to investigate how the illumination of a smartphone at bedtime affects the circadian rhythm and sleep in patients with insomnia. @*Methods@#We recruited two middle-aged patients (one day worker and one shift worker) with insomnia. They used a smartphone more than 12 hours a day, particularly at bedtime. This was a crossover design study, and each patient spent a night at the light control unit twice at a one-week interval, with or without smartphone use. Patients were instructed to look at a smartphone (5–10 lux) under 150 lux of ceiling illumination from 18:00 until lights-off. During the night, without a smartphone, they read a book or newspaper. Saliva was collected every 30 minutes and analyzed for melatonin. Sleep was monitored by polysomnography. @*Results@#The day worker showed a delayed dim light melatonin onset time (DLMO) (21:30 vs. 22:00) and a 38.7% decrease in melatonin levels with smartphone use. For the shift worker, both melatonin and cortisol showed abnormal patterns, and thus DLMO was not determined in either condition. In the day worker, shorter rapid eye movement (REM) latency and increased REM were observed with smartphone use. @*Conclusions@#This study demonstrates that the use of smartphones at bedtime acutely suppresses melatonin secretion and delays the sleep-wake cycle. However, the effect of LAN on melatonin secretion was not apparent in the shift worker with already misaligned circadian rhythm.

Comparison of Sleep Duration, Social Jetlag, and Subjective Sleep Disturbance in Rotating Shift Nurses According to the Chronotype

Purpose@#The purpose of this study was to investigate the sleep duration, social jetlag (SJL), and subjective sleep disturbance according to the individual chronotype in rotating shift nurses. @*Methods@#A total of 344 rotating 3-shift nurses (mean age 28.67 years) were recruited at one university affiliated hospital. They completed the following questionnaires, which were used to assess their chronotype and sleep: the morningness-eveningness questionnaire (MEQ), self-reported sleep duration of work days (SDW shift) and free days (SDF shift) in each shift (day [D], evening [E], night [N]), and sleep disturbance (Insomnia severity index, ISI). SJL shift was calculated as the difference in midsleep (MS = sleep onset+1/2 sleep duration) between work days (MSW) and free days (MSF). @*Results@#Subjects were divided into 3 chronotype groups according to the MEQ; morning (MG, 4.4%) intermediate (IG, 57.8%), and evening groups (EG, 37.8%). SDW D was shortest (4.68 hr) and SDF E was longest (8.93 hr) in the EG. SJL D was longest in the EG (3.77 hr), and SJL N was longest in the MG (7.37 hr). The prevalence of sleep disturbance was 33.3% (MG), 29.6% (IG), and 40.0% (EG), respectively, without any statistical significance. @*Conclusion@#In order to improve the sleep of shift workers, it is recommended that the evening chronotypes should reduce the day shifts and the morning chronotypes should reduce the night shifts. We also propose a study to determine whether these shift assignments can improve the sleep in shift nurses.

Sex Differences in Obstructive Sleep Apnea by Bioelectrical Impedance Analysis

Background@#and Purpose Obesity is known of one of the risk factors for obstructive sleep apnea (OSA). Although body mass index (BMI) can be an indicator for obesity, it does not represent the actual body composition of fat or muscle. We hypothesized that bioelectrical impedance analysis (BIA) can help analyze the fat and muscle distributions in males and females with OSA. @*Methods@#This study screened subjects who visited the Department of Neurology, Samsung Medical Center, Seoul, Korea due to sleep disturbances with symptoms suggestive of OSA from December 2017 to December 2019. All subjects underwent overnight type I polysomnography (PSG) and BIA. @*Results@#PSG and BIA were completed in 2,064 OSA patients who had an apnea-hypopnea index (AHI) of ≥5/hour (77.1% males and 22.9% females). The females had remarkably higher fat indicators and lower muscle indicators. The AHI was significant correlated with all BIA parameters in all OSA patients: body fat mass (ρ=0.286, p<0.001), percentage body fat (ρ= 0.130, p<0.001), visceral fat area (VFA) (ρ=0.257, p<0.001), muscle mass (ρ=0.275, p<0.001), and skeletal muscle mass (SMM) (ρ=0.270, p<0.001). The correlations in males were similar to those in all patients, where those in females were not. In females with OSA, all of the BIA fat indicators were correlated with AHI, whereas the muscle indicators were not. Adjusting age and BMI when analyzing the SMM/VFA ratio showed a strong correlation in males with OSA (p= 0.015) but not in females with OSA (p=0.354). @*Conclusions@#This study has revealed that the body composition of fat and muscle has different patterns in OSA patients. The SMM/VFA as measured using BIA is the factor most significantly associated with AHI in males but not in females after adjusting for age and BMI.

Effects of Organic Light-Emitting Diodes on Circadian Rhythm and Sleep

Objective@#Organic light-emitting diodes (OLEDs) emit less blue light than traditional light-emitting diodes (LEDs), and we previously found that early-night OLED light exposure (LE) delays the melatonin phase by less than LED at a color temperature of 4,000 K. As a follow-up study, we investigated the effects of OLED and LED at a different color temperature (3,000 K) on melatonin profile, sleep, and vigilance. @*Methods@#24 healthy subjects (27.5±5.1 years) were exposed to three light conditions [OLED, LED, and dim light (DL)] from 17:30 to 24:00, in a random order and with a 1-week interval. Saliva samples for melatonin were taken every hour from 18:00 to 24:00. Polysomnography (PSG) and a psychomotor vigilance test (PVT) were performed. @*Results@#Melatonin onset time was significantly delayed under OLED and LED compared with DL, with no significant difference between OLED and LED. The mean melatonin level at 24:00 under LED was lower than that under DL, but there was no significant difference between OLED LE and DL. The percentage of slow wave sleep (N3) in LED was significantly lower than in OLED. @*Conclusion@#Exposure to light in the evening can suppress melatonin secretion late at night and disturb deep sleep, and those effects are slightly worse under LED than OLED.

Effect of Light Emitted by Smartphones at Bedtime on Circadian Rhythm and Sleep: Is It Different between Day Worker and Shift Worker?

Objectives@#Light at night (LAN) can suppress melatonin secretion and thus disturb normal sleep. The aim of this study was to investigate how the illumination of a smartphone at bedtime affects the circadian rhythm and sleep in patients with insomnia. @*Methods@#We recruited two middle-aged patients (one day worker and one shift worker) with insomnia. They used a smartphone more than 12 hours a day, particularly at bedtime. This was a crossover design study, and each patient spent a night at the light control unit twice at a one-week interval, with or without smartphone use. Patients were instructed to look at a smartphone (5–10 lux) under 150 lux of ceiling illumination from 18:00 until lights-off. During the night, without a smartphone, they read a book or newspaper. Saliva was collected every 30 minutes and analyzed for melatonin. Sleep was monitored by polysomnography. @*Results@#The day worker showed a delayed dim light melatonin onset time (DLMO) (21:30 vs. 22:00) and a 38.7% decrease in melatonin levels with smartphone use. For the shift worker, both melatonin and cortisol showed abnormal patterns, and thus DLMO was not determined in either condition. In the day worker, shorter rapid eye movement (REM) latency and increased REM were observed with smartphone use. @*Conclusions@#This study demonstrates that the use of smartphones at bedtime acutely suppresses melatonin secretion and delays the sleep-wake cycle. However, the effect of LAN on melatonin secretion was not apparent in the shift worker with already misaligned circadian rhythm.

Comparison of Sleep Duration, Social Jetlag, and Subjective Sleep Disturbance in Rotating Shift Nurses According to the Chronotype

Purpose@#The purpose of this study was to investigate the sleep duration, social jetlag (SJL), and subjective sleep disturbance according to the individual chronotype in rotating shift nurses. @*Methods@#A total of 344 rotating 3-shift nurses (mean age 28.67 years) were recruited at one university affiliated hospital. They completed the following questionnaires, which were used to assess their chronotype and sleep: the morningness-eveningness questionnaire (MEQ), self-reported sleep duration of work days (SDW shift) and free days (SDF shift) in each shift (day [D], evening [E], night [N]), and sleep disturbance (Insomnia severity index, ISI). SJL shift was calculated as the difference in midsleep (MS = sleep onset+1/2 sleep duration) between work days (MSW) and free days (MSF). @*Results@#Subjects were divided into 3 chronotype groups according to the MEQ; morning (MG, 4.4%) intermediate (IG, 57.8%), and evening groups (EG, 37.8%). SDW D was shortest (4.68 hr) and SDF E was longest (8.93 hr) in the EG. SJL D was longest in the EG (3.77 hr), and SJL N was longest in the MG (7.37 hr). The prevalence of sleep disturbance was 33.3% (MG), 29.6% (IG), and 40.0% (EG), respectively, without any statistical significance. @*Conclusion@#In order to improve the sleep of shift workers, it is recommended that the evening chronotypes should reduce the day shifts and the morning chronotypes should reduce the night shifts. We also propose a study to determine whether these shift assignments can improve the sleep in shift nurses.

Sex Differences in Obstructive Sleep Apnea by Bioelectrical Impedance Analysis

Background@#and Purpose Obesity is known of one of the risk factors for obstructive sleep apnea (OSA). Although body mass index (BMI) can be an indicator for obesity, it does not represent the actual body composition of fat or muscle. We hypothesized that bioelectrical impedance analysis (BIA) can help analyze the fat and muscle distributions in males and females with OSA. @*Methods@#This study screened subjects who visited the Department of Neurology, Samsung Medical Center, Seoul, Korea due to sleep disturbances with symptoms suggestive of OSA from December 2017 to December 2019. All subjects underwent overnight type I polysomnography (PSG) and BIA. @*Results@#PSG and BIA were completed in 2,064 OSA patients who had an apnea-hypopnea index (AHI) of ≥5/hour (77.1% males and 22.9% females). The females had remarkably higher fat indicators and lower muscle indicators. The AHI was significant correlated with all BIA parameters in all OSA patients: body fat mass (ρ=0.286, p<0.001), percentage body fat (ρ= 0.130, p<0.001), visceral fat area (VFA) (ρ=0.257, p<0.001), muscle mass (ρ=0.275, p<0.001), and skeletal muscle mass (SMM) (ρ=0.270, p<0.001). The correlations in males were similar to those in all patients, where those in females were not. In females with OSA, all of the BIA fat indicators were correlated with AHI, whereas the muscle indicators were not. Adjusting age and BMI when analyzing the SMM/VFA ratio showed a strong correlation in males with OSA (p= 0.015) but not in females with OSA (p=0.354). @*Conclusions@#This study has revealed that the body composition of fat and muscle has different patterns in OSA patients. The SMM/VFA as measured using BIA is the factor most significantly associated with AHI in males but not in females after adjusting for age and BMI.

A Sensitive and Specific Liquid ChromatographyTandem Mass Spectrometry Assay for Simultaneous Quantification of Salivary Melatonin and Cortisol:Development and Comparison With Immunoassays

Melatonin and cortisol are clinically important for diagnosing sleep and mood disorders.We developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/ MS) assay for simultaneous measurement of salivary melatonin and cortisol concentrations according to the Clinical and Laboratory Standards Institute guidelines. Additionally, we compared the LC-MS/MS assay with immunoassays, ELISA (Direct Salivary Melatonin Elisa EK-DSM, Bühlmann Laboratories AG, Schönenbuch, Switzerland) and electrochemiluminescence immunoassay (Cortisol II, Roche, Mannheim, Germany), using 121 saliva samples. The LC-MS/MS assay exhibited good performance in terms of linearity, precision, accuracy, limit of detection, lower limit of quantification, extraction recovery, carry-over, and matrix effect. The LC-MS/MS assay and immunoassays showed strong correlation (Pearson’s r = 0.910 for melatonin, r = 0.955 for cortisol), but demonstrated a significant mean bias of 23.2% (range 54.0–143.7%) for melatonin and 48.9% (range 59.7–184.7%) for cortisol. Our LC-MS/MS assay provided more sensitive and reliable salivary melatonin and cortisol quantification results compared with immunoassays.

Sleep-Wake Pattern, Sleep Quality and Daytime Status in Fixed Day-Shift Hospital Workers

Objectives@#Sleep issues are more prevalent in healthcare workers compared to workers in other industries. This study investigated sleep-wake pattern, sleep quality, and daytime status in hospital workers using a Galaxy Watch3 (GW3), a wrist-worn device that uses an accelerometer and heart rate sensor to distinguish sleep and wakefulness. @*Methods@#Multiple sleep parameters including total sleep time (TST) were obtained using a GW3. The Epworth sleepiness scale (ESS), insomnia severity index (ISI), Pittsburgh sleep quality index (PSQI), and bedtime procrastination scale (BPS) were used to assess participants’ status. @*Results@#A total of 70 daytime hospital workers (male, 45.7%; mean age, 35.66±7.79 yr) participated in the monitoring of their sleep-wake patterns for 30 consecutive days. Participants had a mean ESS of 8.14±3.62, ISI of 6.13±3.83, and PSQI of 4.86±2.14. The mean TST was 5.75±0.74 hr (range: 3.42–6.88) during workdays and 5.92±0.92 hr (range: 2.87–8.25) during free days. Chronotype (mid-sleep on freedays corrected for sleep debt accumulated over the work week) was 3.60±1.03 clock hr (range: 1.84–6.69). BPS was negatively correlated with age (rho=-0.27, p=0.022), TST of workdays (rho=-0.53, p<0.001), and TST of free days (rho=-0.43, p<0.001). A higher BPS was associated with larger social jetlag (rho=0.28, p=0.018) and later chronotype (rho=0.41, p<0.001). @*Conclusions@#In this study, 91.5% of daytime hospital workers suffered from chronic sleep insufficiency (<7 hr during both workdays and free days) although their daytime sleepiness or subjective sleep were not poor. Individuals with a later chronotype had poorer sleep quality and worse sleep procrastination behavior.

A case of ROHHAD (rapid-onset obesity with hypothalamic dysregulation, hypoventilation, and autonomic dysregulation) syndrome in an 11-year-old girl

Rapid-onset obesity with hypoventilation, hypothalamic, and autonomic dysregulation (ROHHAD) syndrome is a rare disease characterized by rapid progression of obesity and central hypoventilation with autonomic and endocrine dysregulation. There is no gold-standard diagnostic method for ROHHAD syndrome; it is diagnosed based on a years-long clinical course. For this reason, diagnosis of ROHHAD syndrome is often delayed. In particular, ROHHAD has a high mortality rate due to cardiopulmonary arrest when quick diagnosis and appropriate intervention of central sleep apnea are not timely. We report a case in which an 11-year-old girl with central sleep apnea was diagnosed with ROHHAD syndrome: the clinical course with early breathing intervention using noninvasive positive pressure ventilation. We emphasize the importance of respiratory interventions in the clinical course of ROHHAD syndrome.

Sex Differences in Etiologies of Sleep Disorders

Objectives@#To investigate the etiologies of sleep disorders according to sex. @*Methods@#We enrolled 1,270 patients who complained of insomnia (n=328) or sleep apnea (n=942) for more than 6 months and classified them into primary insomnia (PI, n=120), comorbid obstructive sleep apnea with insomnia (COMISA, n=146), and obstructive sleep apnea (OSA, n=884) groups based on their polysomnography (PSG) findings, demographics, sleep-related symptoms, and questionnaire results (Insomnia Severity Index and Epworth Sleepiness Scale). @*Results@#The highest prevalence of females was observed in PI (71.7%), and the lowest in the OSA group (15.6%). Males were more prevalent than females in the COMISA group (58.2% vs. 41.8%). Regarding the etiology of insomnia, half of the male patients with complaints of insomnia had OSA, while only one-third of the females had OSA. Thirteen percent of female who complained of OSA-related symptoms were diagnosed as normal. There were few differences in PSG data between female and male patients in the PI and COMISA groups. Females with OSA showed longer total sleep time than males with OSA in PSG. The self-reported questionnaire responses of patients in the COMISA and PI groups were similar, and PSG data of patients in the COMISA and OSA groups were comparable regardless of sex. @*Conclusions@#Females and males have different sleep perceptions and sleep-related complaints. Thus, PSG must be carried out to clarify the etiology of sleep disorders and ensure appropriate treatment is provided.

The Mediating Effect of Depression in the Relationship between Sleep Misperception and Insomnia Severity among Insomnia Patients

Objectives@#Sleep misperception is the underestimation of perceived total sleep time compared to actual total sleep time. It is observed in approximately 50% of patients with insomnia. Insomnia patients with sleep misperception report significantly higher depression than those without sleep misperception. Depression is one of the most consistent risk factors for predicting insomnia. Therefore, this study attempted to confirm the mediating effect of depression in exacerbating insomnia. @*Methods@#This study included 77 male and female aged 18–40 years who met diagnostic criteria for insomnia disorder based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Depression and insomnia severity were measured using self-report questionnaires, and actigraphy data were collected for 1 week. The sleep misperception index was calculated using the sleep diary and actigraphy. @*Results@#The Pearson correlation analysis was performed to examine the relationships between sleep misperception, insomnia, and depression. Sleep misperception was positively associated with depression (r=0.399, p<0.01). There was also a significant positive correlation between depression and insomnia severity (r=0.591, p<0.01). However, there was no significant correlation between sleep misperception and insomnia severity (r=0.210, p=0.07). Depression was found to have a full mediating effect on the relationship between sleep disturbance and severity of insomnia (n=77, B=6.1688, 95% confidence interval=2.9960, 10.4562). @*Conclusions@#This study verified the mediating effect of depression on the relationship between sleep misperception and insomnia severity. The results highlight the importance of considering depression and sleep misperception in insomnia treatment.

Relationship of Sleep Quality and Cognitive Function in Patients with Mild Cognitive Impairment and Subjective Memory Impairment

Objectives@#To investigate the relationship between subjective sleep quality and cognitive function in patients with subjective memory impairment (SMI), a self-perceived cognitive decline without objective cognitive impairment, and amnestic mild cognitive impairment (aMCI). @*Methods@#We enrolled 246 patients with memory impairment (126 with SMI and 120 with aMCI) who fulfilled the Korean version of the Pittsburgh Sleep Quality Index (PSQI-K), a standardized battery of neuropsychological tests, and mood questionnaires. Based on the PSQI-K cutoff point of 5, patients were classified as good sleepers (GS) or poor sleepers (PS). @*Results@#There was no difference in the proportion of GS and PS between patients with SMI and aMCI [68 PS (54.0%) in SMI vs. 62 PS (51.7%) in aMCI, p>0.05]. Demographics did not differ between the SMI and aMCI groups. In both the SMI and aMCI groups, PS had worse sleep-wake parameters, such as sleep latency, total sleep time, and sleep efficiency, than GS and reported worse performance in all PSQI-K subcomponents. Neuropsychological data were not different between GS and PS, except for the Stroop word test in patients with aMCI. Depressive scores were worse in PS than in GS in both the SMI and aMCI groups. @*Conclusions@#We observed that cognitive function was not significantly different between GS and PS in both the SMI and aMCI groups, except in the Stroop word test in the aMCI group, while PS had more depressive mood than GS in both groups. This suggests that subjective sleep quality may depend on mood disturbances in patients with mild cognitive impairment.