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.

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.

Objectives: Circadian misalignment may increase the risk of obesity and related obstructive sleep apnea (OSA). Considerable young adults have social jetlag (SJL), which is defined as the time discrepancy between workdays and free days. We aim to evaluate the relationship between SJL and sleep and respiratory disturbance in patients with untreated OSA patients. Methods: A total of 180 OSA patients under the age of 50 [mean 38.3±8.0 y, 93.3% male, mean apnea-hypopnea index (AHI) 38.2±27.4 /h] were recruited from the university affiliated sleep clinic and fulfilled sleep-related questionnaires including Munich Chronotype Questionnaire (MCTQ). SJL was defined as the difference in sleep midpoints between work and free days. Patients were divided into three groups with SJL less than 1 hour, 1–2 hours, and 2 hours or more and the clinical and sleep data of each group were compared. Results: 51.6% (n=93) suffered from significant SJL (≥1 h). Patients with ≥2h of SJL (16.6%, n=30) had the largest neck circumference (NC). AHI and sleep parameters were not significantly different among groups except lowest oxygen saturation (LoS) was the lowest in the group of ≥2 h. SJL was positively correlated with body mass index and NC and negatively correlated with LoS after adjusting for age and sex. Conclusions About a half of young adults with OSA have significant SJL more than 1 h. This study suggests that SJL is associated with being overweight, while it seems not increase the severity of OSA nor deteriorate sleep quality in young adults.

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.

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.

Objectives: Circadian misalignment may increase the risk of obesity and related obstructive sleep apnea (OSA). Considerable young adults have social jetlag (SJL), which is defined as the time discrepancy between workdays and free days. We aim to evaluate the relationship between SJL and sleep and respiratory disturbance in patients with untreated OSA patients. Methods: A total of 180 OSA patients under the age of 50 [mean 38.3±8.0 y, 93.3% male, mean apnea-hypopnea index (AHI) 38.2±27.4 /h] were recruited from the university affiliated sleep clinic and fulfilled sleep-related questionnaires including Munich Chronotype Questionnaire (MCTQ). SJL was defined as the difference in sleep midpoints between work and free days. Patients were divided into three groups with SJL less than 1 hour, 1–2 hours, and 2 hours or more and the clinical and sleep data of each group were compared. Results: 51.6% (n=93) suffered from significant SJL (≥1 h). Patients with ≥2h of SJL (16.6%, n=30) had the largest neck circumference (NC). AHI and sleep parameters were not significantly different among groups except lowest oxygen saturation (LoS) was the lowest in the group of ≥2 h. SJL was positively correlated with body mass index and NC and negatively correlated with LoS after adjusting for age and sex. Conclusions About a half of young adults with OSA have significant SJL more than 1 h. This study suggests that SJL is associated with being overweight, while it seems not increase the severity of OSA nor deteriorate sleep quality in young adults.

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.

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.

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.

Purpose: This quasi-experimental single group study aimed to confirm the effects of discharge education using a systematic discharge education program on anxiety and parenting confidence in mothers of premature babies. Methods: This study conducted discharge education for 3 to 5 days prior to the discharge of 29 mothers of premature babies born in the neonatal intensive care unit. Data were collected between April 1, 2021, to June 30, 2021, and were examined. The hypotheses were analyzed using the Wilcoxon signed-rank test. Results: Discharge education using a systematic discharge education program was effective in increasing the parenting confidence of mothers with premature babies (z=-3.839, p<0.001). However, it was not effective in reducing anxiety (z=-1.712, p=0.087). Conclusion The effects of the systematic discharge education program development and discharge education systematized discharge nursing education, reduced mothers’ anxiety in raising premature babies at home after discharge, and contributed to improving parenting confidence.