Ambient temperature and humidity are important factors that determine sleep quality. In real-life situations where bedding and clothing are used, sleep is affected more by heat than by cold exposure. Effects of thermal environment on sleep are strongly related to thermoregulation. Increased skin temperature（Tsk） and decreased core body temperature at sleep onset period, and stable Tsk and bed climate during sleep are important for maintaining sleep. Heat exposure increases wakefulness and decreases rapid eye movement sleep（REM） and slow wave sleep（SWS）. In aged subjects, heat exposure increases wakefulness and decreases REM, while no effect is observed on SWS. Furthermore, heat exposure reduces the core body temperature decrease, and increases Tsk, whole body sweat loss, and bed climate humidity both in young and aged subjects. Humid heat exposure further affects sleep stages and thermoregulation. Although the ambient temperature is cold, effects of using electric blankets on sleep and thermoregulation showed similar result to heat exposure, with subjectively dried mouth sensation in the morning. These results indicate that increased thermal stress by humid heat or heated bed climate affects sleep and thermoregulation and might increase dried mouth sensation in the morning.

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Insomnia is thought to be common in clinical settings and is reported to be highly comorbid with obstructive sleep apnea （OSA）. It is important for physicians to have appropriate understanding for the treatment of insomnia. Because both insomnia and OSA are closely related to life style-related diseases, such as hyper tension and diabetes mellitus, treatment of insomnia is thought to be important for preventing these diseases.
Sleep hygiene education is the most important for the treatment of insomnia before starting hypnotic treatment. Single kind and usual doses of benzodiazepines and benzodiazepine receptor agonists, which are the most frequently used for the treatment of insomnia, were effective and safe for insomnia comorbid with mild to moderate degree of OSA. On the other hand, high-dose use of these hypnotics was reported to deteriorate symptoms of OSA. Therefore, physicians should not use high-dose or multi-kind use of these hypnotics for insomnia patient comorbid with OSA. Recently, a melatonin receptor agonist and orexin receptor antagonist have been reported to be effective and safe for insomnia patient comorbid with OSA. Similarly, cognitive behavioral therapy as non-hypnotic treatment is expected to be alternative treatment for insomnia comorbid with OSA. In the future, it will be needed to confirm these effectiveness and safety for the appropriate treatment strategy of insomnia comorbid with OSA.

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Objective: All-night polysomnography （PSG） is a useful tool for evaluating sleep quality. However, it requires subjects to sleep in an unfamiliar environment, which can influence sleep quality. Moreover, PSG is labor-intensive, timeconsuming, and expensive. We evaluated a portable two-channel electroencephalogram （EEG） monitoring system and compared the signals obtained from the device with those of simultaneously recorded full PSG.
Methods: Signals obtained from two-channel EEG were comparing with simultaneously recorded full PSG signals. Sleep stages were scored using the American Academy of Sleep Medicine Manual for Scoring Sleep 2007. The epochby-epoch percent agreement and Cohen’s kappa coefficient were used for agreement evaluation of sleep stage in both devices.
Results: The participants were healthy Japanese volunteers （mean （standard deviation）: age: 20.9 （1.8） years; seven women and nine men）. In epoch-by-epoch comparison, the average agreement and kappa value of sleep stages between two-channel EEG and PSG were 0.83 （0.04） and 0.75 （0.05）, respectively. Kappa coefficients showed strong agreement for stage R （REM: rapid eye movement）, stage W （wake）, stage N3 （non-REM: NREM 3）, and stage N2 （NREM 2）（0.86（0.09）, 0.76（0.12）, 0.74（0.15） and 0.73（0.06）, respectively） and weak agreement for stage N1（NREM 1）（0.44（0.13））.
Conclusion: These results demonstrate that two-channel EEG facilitates home sleep monitoring and exhibits acceptable agreement with PSG. Therefore, this tool may be suitable for use in epidemiological and intervention studies.

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Objectives: Oral appliance （OA） have reported to be an efficacious treatment option for obstructive sleep apnea （OSA） in 60−70% of patients. The objective of this study was to determine the utility of continuous positive airway pressure（CPAP） optimum pressure as a predictor of the efficacy of OA treatment in OSA.
Methods: A total of 20 patients with polysomnographically diagnosed OSA and treated by CPAP were recruited for this study. Responders were defined as a reduction in apnea-hypopnea index （AHI） ‹ 10/h in addition to a › 50% reduction in baseline AHI. We compared the CPAP optimum pressure of responders and non-responders with OA treatment.
Results: The CPAP optimum pressure was significantly lower in responders compared with non-responders （7.4 [6.0−8.6] vs 10.5 [8.2−12.3], p ‹ 0.01）. The cut-off value of the CPAP optimum pressure for deterministic diagnosis was 7.9cmH2O. The cut-off value for exclusive diagnosis was 10.5cmH2O.
Conclusions: These results indicate that the CPAP optimum pressure may have significant clinical utility in the predicting success of OA treatment.

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Objectives: We present a case of severe obstructive sleep apnea（OSA） in which oral appliance（OA） therapy had no significant efficacy and there was poor compliance of continuous positive airway pressure （CPAP） therapy related to pressure intolerance, but in which combination therapy of OA and CPAP reduced optimal pressure and improved compliance.
Methods: The patient was a 69-year-old man with no significant past medical history who was diagnosed as having severe obstructive sleep apnea （AHI: 92.5/h, lowest SpO2: 82%） by polysomnography （PSG）. We recommended CPAP therapy due to the severe OSA, but the patient refused this therapy and desired OA therapy. First, OA therapy was applied to this patient. After OA insertion for 2 months, the patient reported reduction of snoring and wore the OA comfortably; the efficacy of OA therapy in OSA was evaluated by PSG.
Results: PSG under OA showed an improvement of OSA in AI from 81.3/h to 33.1/h, but residual findings in AHI: 73.2/h. Secondly, we adopted CPAP therapy because of inadequacy of the efficacy of OA therapy. In PSG with CPAP titration, optimal pressure is 17cmH2O. After wearing CPAP for 3 months, the patient reported insomnolence because of discomfort of airflow from CPAP. The data of compliance of CPAP therapy were actual days utilized: 54.8%, compliance per day: 3 h 45 min, and % of days utilized ≥ 4 h/d （%）: 23.8%. We considered that a cause of the poor compliance of CPAP therapy was that the optimal pressure was too high. Thirdly, we adopted combination therapy of OA and CPAP for the purpose of reducing the optimal pressure of CPAP. The optimal pressure with CPAP titration PSG wearing OA decreased from 17cmH2O to 11cmH2O. The combination therapy showed improvement of compliance in terms of actual days utilized from 54.8% to 96.8%, in terms of compliance per day from 3 h 45 min to 4 h 8 min, and in terms of % of days utilized ≥ 4 h/d from 23.8% to 54.8%.
Conclusions: This report suggests that wearing an OA decreased the optimal pressure of CPAP and improved the compliance of CPAP therapy for severe OSA. It is important that, in the selection of treatment for patients with OSA, we adopt not only OA therapy or CPAP therapy, but also combination therapy of OA and CPAP.

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