The risk of cardiovascular disease is known to be increased in obstructive sleep apnea syndrome (OSAS). Its mechanism can be explained by the observation that the sympathetic tone increases due to repetitive apneas accompanied by hypoxias and arousals during sleep. Heart rate variability (HRV) representing cardiac autonomic function is mediated by respiratory sinus arrhythmia, baroreflex-related fluctuation, and thermoregulation-related fluctuation. We evaluated the heart rate variability of OSAS patients during night to assess their relationship with the severity of the symptoms. We studied overnight polysomnographies of 59 male untreated OSAS patients with moderate to severe symptoms (mean age 45.4± 11.7 yr, apnea-hypopnea index [AHI]=43.2±23.4 events per hour, and AHI >15). Moderate (mean age 47.1±9.4 yr, AHI=15-30, n=22) and severe (mean age 44.5±12.9 yr, AHI >30, n=37) OSAS patients were compared for the indices derived from time and frequency domain analysis of HRV, AHI, oxygen desaturation event index (ODI), arousal index (ArI), and sleep parameters. As a result, the severe OSAS group showed higher mean powers of total frequency (TF) (p=0.012), very low frequency (VLF) (p= 0.038), and low frequency (LF) (p=0.002) than the moderate OSAS group. The LF/HF ratio (p=0.005) was higher in the severe group compared to that of the moderate group. On the time domain analysis, the HRV triangular index (p=0.026) of severe OSAS group was significantly higher. AHI was correlated best with the LF/HF ratio (rp=0.610, p<0.001) of all the HRV indices. According to the results, the frequency domain indices tended to reveal the difference between the groups better than time domain indices. Especially the LF/HF ratio was thought to be the most useful parameter to estimate the degree of AHI in OSAS patients.

ObjectiveLow-income adults are considered to be a group at high risk for suicide. We sought to examine the effect of type D personality and other socio-demographic factors on suicidality in low-income, middle-aged Koreans.MethodsIn total, 306 low-income, middle-aged Koreans [age: 49.16±5.24 (40-59) years, 156 males, 150 females] were enrolled from the Korean National Basic Livelihood Security System. Socio-demographic data, including employment status, income, health, marital status, and educational attainment, were gathered. Beck's 19-item Scale for Suicidal Ideation (SSI) was applied to evaluate suicidality, and the DS14 was used to assess type D personality.ResultsUnemployment (p<0.01) and absence of spouse (p=0.03) predicted higher SSI scores independent of other socioeconomic factors. All type D personality scores [i.e., negative affectivity (NA), social inhibition (SI), and total score] predicted higher SSI scores independent of all socioeconomic factors (all, p<0.001). Subjects with type D personality had higher SSI scores (p<0.001), and the association between suicidality and socio-demographic factors (employment or physical health) could be found only in subjects without type D personality.ConclusionType D personality was a risk factor for suicide in low-income Koreans, independently from socio-economic factors. In addition, the socio-demographic factors were less prominently associated with suicidality in those with type D personality.

The ain of this study was to access how self-reported sleep latency (SRSL) was affected by sleep habits, mood, and circadian rhythm in postmenopausal women. Subjects (n=384, 67.9±7.7 yr) completed sleep and mood questionnaires, sleep log and actigraphic data. The major urinary melatonin metabolite (6-sulphatoxymelatonin, aMT6s) was assayed in fractional urine specimens for two 24-hr intervals. Although SRSL (26.5±24.4 min) and actigraphic sleep latency (ASL; 27.8±20.0 min) were correlated (rs=0.361, p<0.001), the short SRSLs tended to be underestimated whereas the long SRSLs tended to be overestimated as compared to ASL. SRSL was positively correlated with the scales of insomnia, mood and hot flash, hypertension, use of anti-hypertensive drugs and the acrophase and the offset of aMT6s. SRSL was negatively correlated with the global assessment of functioning scale in DSM-IV (GAF scale), and light exposure and wrist activity. Multiple linear regression analysis showed that the best-fit model to predict SRSL was light exposure, GAF scale, and use of anti-hypertensive drugs. SRSL may be determined by psychophysiological factors as well as circadian rhythm function. Therapeutic approaches suggested for trouble falling asleep might include increased daylight exposure, improvements in general health, and modification of anti-hypertensive pharmacotherapy.

Background This study aimed to determine if sleep disturbances may mediate the relationship between panic symptoms and depression in patients with panic disorder (PD). Methods Electronic medical records were retrospectively reviewed for 110 consecutive patients with diagnosed PD in an outpatient clinic between October 2018 and December 2019. Measurements include the PD Severity Scale, Beck Depression Inventory-II (BDI-II) and Insomnia Severity Index (ISI). Statistical analyses were performed to assess any potential relationship between PD, insomnia and depression. Results Of the PD patients, 88 (80%) and 89 (80.9%) had comorbid depression (BDI-II ≥ 14) and insomnia (Korean version of the ISI ≥ 8), respectively. In a mediation model using insomnia as the mediating variable, the total effect of panic symptom severity on depression was significant ( t = 7.23, P < 0.001). There were significant effects of panic symptoms on insomnia ( t = 4.62, P < 0.001) and of insomnia on depression ( t = 6.69, P < 0.001). The main effect of panic symptom severity on depression was also significant, after controlling for the effect of insomnia ( t = 5.10, P < 0.001), suggesting partial mediation. Conclusion Both depressive symptoms and insomnia are common in patients with PD and depression was partially mediated by insomnia in these patients. These results suggest that an intervention for insomnia in patients with PD might help prevent the development of depression.