LPS and its relationship with subjective-objective discrepancies of sleep onset latency in patients with psychiatric disorders.

Subjective-objective discrepancies in sleep onset latency (SOL), which is often observed among psychiatric patients, is attributed partly to the definition of sleep onset. Recently, instead of SOL, latency to persistent sleep (LPS), which is defined as the duration from turning out the light to the first consecutive minutes of non-wakefulness, has been utilized in pharmacological studies. This study aimed to determine the non-awake time in LPS that is most consistent with subjective sleep onset among patients with psychiatric disorders. We calculated the length of non-awake time in 30-s segments from lights-out to 0.5-60 min. The root mean square error was then calculated to determine the most appropriate length. The analysis of 149 patients with psychiatric disorders showed that the optimal non-awake time in LPS was 12 min. On the other hands, when comorbid with moderate or severe obstructive sleep apnea (OSA), the optimal length was 19.5 min. This study indicates that 12 min should be the best fit for the LPS non-awake time in patients with psychiatric disorders. When there is comorbidity with OSA, however, a longer duration should be considered. Measuring LPS minimizes discrepancies in SOL and provides important clinical information.

A Study of Factors Causing Sleep State Misperception in Patients with Depression.

Purpose: Sleep state misperception, which is the discrepancy between subjective and objective sleep, is often observed in patients with depression. This phenomenon may delay the remission of depression. Previous studies have focused on the total sleep time (TST) misperception, with many of these studies using actigraphy. Thus, our study investigated depressed patients with the exploratory aim of clarifying factors associated with the sleep state misperception including the wake after sleep onset (WASO) misperception, with their objective sleep additionally evaluated by polysomnography (PSG). Patients and Methods: We conducted a cross-sectional study. Before undergoing overnight PSG monitoring, 40 patients with depression completed questionnaires that included the Beck Depression Inventory (BDI), Epworth sleepiness scale, Temperament and Character Inventory, and the Pittsburgh sleep quality index. Patients were also asked to estimate their subjective sleep duration after they woke up in the morning. Based on this data, we calculated the misperception using the following formula: subjective sleep duration minus objective sleep duration. We compared each factor between negative and positive misperception groups and the multiple regression analysis was performed for TST and WASO misperception, respectively. Results: Although sleep architectures, age, severity of depression and obstructive sleep apnea (OSA) exhibited differences in underestimating or overestimating the WASO, only sex differences were associated with underestimating or overestimating their total sleep time (TST). Moreover, BDI, the severity of OSA, sleep architectures (N1% and N2%), and benzodiazepine (BZD) use were significantly correlated with WASO misperception, whereas only OSA severity was significantly correlated with TST misperception. A subsequent multiple regression analysis demonstrated the BDI was independently correlated with the WASO misperception (ß=0.341, p=0.049). Conclusion: In clinical practice, interventions especially for OSA, and the reduction of depressive symptoms are an important method for improving patient sleep perception. Moreover, current results suggest that BZD prescriptions should be avoided as well.

Patient characteristics affecting accurate detection of sleep apnea using a bed sheet-type portable monitor.

PURPOSE: Although performed inside a laboratory, attended polysomnography (PSG) has long been the gold standard for the diagnosis of sleep apnea. However, high costs and long wait times have led to the development of home-based portable monitoring devices. A bed sheet-shaped device called SD102 (Suzuken Co., Nagoya, Japan) has been developed, and its accuracy in evaluating sleep apnea is becoming evident. The purpose of this study was to confirm the accuracy of SD102 in evaluating sleep apnea and to investigate patient characteristics that may contribute to inaccurate test results in patients with suspected obstructive sleep apnea (OSA). METHODS: One hundred and eighty-nine patients simultaneously underwent PSG and portable monitoring by using a home sleep apnea testing (HSAT) device. A blinded, experienced technologist using the American Academy of Sleep Medicine criteria versions 2.1 and 2.3 scored the PSG data and HSAT device data, respectively. RESULTS: The respiratory event index (REI) by HSAT significantly correlated with the apnea-hypopnea index (AHI) by PSG (r = 0.974, p < 0.001). HSAT sensitivity, specificity, and positive and negative predictive values of 0.99, 0.83, 0.95, and 0.97, respectively. Body mass index and arousal index were significantly associated with the difference between REI from SD102 HSAT and AHI from PSG. CONCLUSIONS: This study demonstrates the good agreement between REI and AHI in patients with suspected OSA and suggests that understanding the limitations of different testing methods may help in the accurate detection of OSA.

Influence of sleep duration on cortical oxygenation in elderly individuals.

AIM: Short sleep duration is a risk factor for cardiovascular diseases. Cerebral blood flow and its regulation are affected by pathological conditions commonly observed in the elderly population, such as dementia, atherosclerosis, diabetes mellitus (DM), stroke, and hypertension. The purpose of this study was to examine the influence of sleep duration on cortical oxygenated hemoglobin (OxyHb) using near-infrared spectroscopy (NIRS). METHODS: Seventy-three individuals (age, 70.1 ± 3.9 years, 51 men and 22 women) participated in this study. Cortical OxyHb levels were measured with NIRS. We evaluated age, body mass index (BMI), smoking status, alcohol intake, sleep duration, hypertension, DM, and hyperlipidemia using a questionnaire. Blood pressure was measured using plethysmography. RESULTS: Peak OxyHb and area under the NIRS curve significantly decreased in participants with sleep duration <7 h compared with those with sleep duration ≥7 h (0.136 ± 0.212 mM·mm vs 0.378 ± 0.342 mM·mm, P = 0.001; 112.0 ± 243.6 vs 331.7 ± 428.7, P = 0.012, respectively). Sleep duration was significantly correlated with peak OxyHb level and area under the NIRS curve (r = 0.378, P = 0.001; r = 0.285, P = 0.015, respectively). Multiple regression analysis, including age, BMI, sex, smoking status, alcohol intake, sleep duration, hypertension, DM, and hyperlipidemia revealed that sleep duration was the only significant independent factor associated with peak OxyHb and area under the NIRS curve (ß = 0.343, P = 0.004; ß = 0.244, P = 0.049, respectively), and smoking status was independently correlated with time to the peak OxyHb (ß = -0.319, P = 0.009). CONCLUSION: Sleep duration may be an important factor that influences cortical oxygenation in the elderly population.