Altered distribution of resting periods of daily locomotor activity in patients with delayed sleep phase disorder.

Delayed sleep phase disorder (DSPD) and mood disorders have a close relationship. However, the shared mechanisms by DSPD and mood disorders have not been well-elucidated. We previously found that micro-fluctuations in human behaviors are organized by robust statistical laws (behavioral organization), where the cumulative distributions of resting and active period durations take a power-law distribution form and a stretched exponential functional form, respectively. Further, we found that the scaling exponents of resting period distributions significantly decreased in major depressive disorder (MDD). In this study, we hypothesized that DSPD had similar characteristics of the altered behavioral organization to that of MDD. Locomotor activity data were acquired for more than 1 week from 17 patients with DSPD and 17 age- and gender-matched healthy participants using actigraphy. We analyzed the cumulative distributions of resting and active period durations in locomotor activity data and subsequently derived fitting parameters of those distributions. Similar to patients with MDD, we found that resting period distributions took a power-law form over the range of 2-100 min, with significantly lower values of scaling exponents γ in patients with DSPD compared with healthy participants. The shared alteration in γ suggests the existence of similar pathophysiology between DSPD and MDD.

Normalization of breathing with adenotonsillectomy in Japanese pediatric OSA.

OBJECTIVE: Since reports on surgical results for pediatric obstructive sleep apnea (OSA) in Japan are insufficient for debate, this study aimed to evaluate the feature of Japanese OSA children and surgical result and document whether is obesity and affecting factor similar to non-Asian countries. METHODS: This is a retrospective study. A total of 242 children with OSA at the Department of Otolaryngology and the Good Sleep Center, Nagoya City University Hospital and the Toyohashi Mates Sleep Disorders Center were included in the study. All children underwent pre- and postsurgical polysomnography. OSA was defined as an apnea hypopnea index (AHI) 5 or greater. Pre- and postsurgical respiratory parameters were compared using paired T test. RESULTS: Normalization of breathing after surgery for OSA children was 40% with AHI < 2 and 85% with AHI < 5. Japanese OSA children are not as obese as OSA children in many non-Asian countries. However, the normalization of breathing as a result of surgery in Japanese OSA children does not differ much from non-Asian countries. CONCLUSION: Japanese pediatric OSA that is not normalized by surgery may be affected by factors other than obesity.

Wearing blue light-blocking glasses in the evening advances circadian rhythms in the patients with delayed sleep phase disorder: An open-label trial.

It has been recently discovered that blue wavelengths form the portion of the visible electromagnetic spectrum that most potently regulates circadian rhythm. We investigated the effect of blue light-blocking glasses in subjects with delayed sleep phase disorder (DSPD). This open-label trial was conducted over 4 consecutive weeks. The DSPD patients were instructed to wear blue light-blocking amber glasses from 21:00 p.m. to bedtime, every evening for 2 weeks. To ascertain the outcome of this intervention, we measured dim light melatonin onset (DLMO) and actigraphic sleep data at baseline and after the treatment. Nine consecutive DSPD patients participated in this study. Most subjects could complete the treatment with the exception of one patient who hoped for changing to drug therapy before the treatment was completed. The patients who used amber lens showed an advance of 78 min in DLMO value, although the change was not statistically significant (p = 0.145). Nevertheless, the sleep onset time measured by actigraph was advanced by 132 min after the treatment (p = 0.034). These data suggest that wearing amber lenses may be an effective and safe intervention for the patients with DSPD. These findings also warrant replication in a larger patient cohort with controlled observations.

An Open-Labeled Trial of Ramelteon in Idiopathic Rapid Eye Movement Sleep Behavior Disorder.

STUDY OBJECTIVES: Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by REM sleep without atonia and elaborate motor activity in association with dream mentation. The melatonin receptor agonist ramelteon has been documented as being effective in two patients with secondary RBD. However, there are no reports on ramelteon treatment for idiopathic RBD. METHODS: In an open-labeled trial, we treated 12 consecutive patients with idiopathic RBD for at least 4 w with 8 mg ramelteon given within 30 min before bedtime. RESULTS: Ramelteon treatment did not have a clear effect on REM sleep without atonia or an RBD severity scale measured by video-supported polysomnography. However, clinical assessment using a visual analog scale showed a trend toward significance and there were also definitely positive changes in some individual cases. Ramelteon was well tolerated in most patients, with minor side effects. CONCLUSIONS: Considering that ramelteon is associated with few side effects, further study may ascertain whether patients with RBD could be effectively treated by ramelteon, especially when clonazepam may not be suitable due to its side effects. COMMENTARY: A commentary on this article appears in this issue on page 643.

Seasonal variation in a clinical referral pediatric cohort at risk for obstructive sleep apnea.

OBJECTIVE: The present study was carried to examine the hypothesis that the severity of obstructive sleep apnea (OSA) in a clinical referral population of children would manifest seasonal variability in their polysomnographic findings. METHODS: The study population comprised consecutive children referred for evaluation of habitual nighttime snoring, parentally witnessed apnea during sleep, and difficult or noisy breathing during sleep. A total of 554 children were identified as eligible and underwent full-night polysomnography (PSG). Monthly fluctuation patterns in PSG measures were assessed in 2 age groups (<6 and ≥ 6 years old). RESULTS: In the younger group, the lowest AHI was found in the month of August (9.5 ± 1.7/hrTST) while December emerged as the month with the lowest AHI for the older group (8.7 ± 2.3/hrTST). The highest AHI was in January (24.8 ± 7.5/hrTST) in the group ≥ 6 years old, and in March (32.7 ± 6.9/hrTST) in the younger group. CONCLUSION: Seasonal changes are present in children with clinically symptomatic OSA and differ among younger and older children, with global trends toward improved AHI during summer, especially in younger children. Future studies should be conducted to define a "correction factor" for the month of PSG assessment that will enable accurate decision making when evaluating symptomatic children with habitual snoring.

Sleep quality of mechanically ventilated patients sedated with dexmedetomidine.

PURPOSE: Dexmedetomidine is thought to activate an endogenous pathway that naturally promotes non-rapid eye movement (NREM) sleep. Dexmedetomidine may induce restorative sleep, that is, NREM stage 3 and 4 (slow wave sleep; SWS) or sleep continuity in mechanically ventilated patients. Few data have been published, however, on the sleep characteristics of mechanically ventilated patients during dexmedetomidine infusion. METHODS: We recorded polysomnography (PSG) for 24 h in mechanically ventilated patients sedated with dexmedetomidine. Dexmedetomidine (0.2-0.7 µg/kg/h) was administered intravenously to maintain the Richmond Agitation-Sedation Scale between -1 and -4 only during the nighttime (9:00 p.m. to 6:00 a.m.). During the daytime, we interrupted the sedatives and analgesics unless the patient complained of discomfort. When this occurred midazolam or opioids were administered intermittently. Sleep stages and the frequency of arousal/awakening during the nighttime were analyzed using Rechtschaffen and Kales criteria. RESULTS: For the ten mechanically ventilated adult patients recruited into the study, the median total sleep time (TST) during the night was 4.7 h (IQR, 4.2-8.1 h), and 78 % of sleep occurred during the night (median 78 %, IQR: 69-88 %). Sleep architecture was exclusively NREM sleep stage 1 (median 28.9 % of TST) and stage 2 (median 71.2 % of TST). Neither SWS (median 0 % of TST) nor rapid eye movement (REM) sleep (median 0 % of TST) was observed. Median frequency of arousals/awakenings was 9.3/h (IQR, 3-19.5/h). CONCLUSIONS: In mechanically ventilated patients, nighttime infusion of dexmedetomidine preserved the day-night cycle of sleep but induced severely disturbed sleep architecture without evidence of SWS or REM sleep.

[Chronic renal failure (hemo-dialysis patients)].

The feature of a dialysis patient's sleep disorder is that deviation with a feeling of subjective sleep and an objective sleep disturbance is large, and subjective symptoms are scarce considering serious sleep disorders. The feature of a dialysis patient' s sleep disturbance is characterized by increase in time to awake on bed and the fragmentation of sleep, which lead to reduction in sleeping hours. The prevalence of SAS (sleep apnea syndrome) in the dialysis patient is several times higher compared with the commoner. The prevalence of RLS (restless legs syndrome) in Japanese dialysis patient was almost even with Westerners patient. Otherwise it tends to underestimate sleep disturbance, our questionary survey revealed high prevalence of subjective sleep complaints in dialysis patients. The realities of dialyzed patient' s sleep disturbance might be more serious than we think.

Modified thoracic impedance plethysmography to monitor sleep apnea syndromes.

BACKGROUND AND PURPOSE: In order to identify sleep disorders by thoracic impedance plethysmography (TIP), we propose several new techniques: the application of an adaptive filter, a scaled Fourier linear combiner (SFLC) to eliminate cardiac-derived fluctuation in the impedance waveform, and the use of heart rate variability (HRV) to ascertain whether the airflow is obstructed. PATIENTS AND METHODS: Laboratory simulation experiments on four healthy individuals and actual overnight measurements on five patients with sleep disorders were carried out. Amplified thoracic impedance change (DeltaZ), ECG, a phonocardiograph, a pneumotachograph and a standard polysomnograph were recorded. The SFLC was applied to DeltaZ to selectively extract the cardiac-synchronous component (DeltaZ(CSC)), and the remainder of the waveform (DeltaZ(REM)) was low-pass filtered to estimate the waveform driven by respiration. The HRV was divided into respiratory synchronous (HRV(R)) and low frequency (HRV(L)) components. RESULTS: The SFLC could drastically extract DeltaZ(CSC) from DeltaZ and thereby demonstrate a DeltaZ(REM) pattern quite similar to the flow-volume curve of the pneumotachograph. Central sleep apnea could be identified as the cessation of DeltaZ(REM) and concomitant attenuation of HRV(R). Obstructive sleep apnea could be identified as the maintenance of rhythmic but attenuated variations of DeltaZ(REM) accompanied by asynchronous fluctuation of HRV(R) against DeltaZ(REM). Central hypopnea could be identified as a normal but attenuated waveform in both DeltaZ(REM) and HRV(R). A large fluctuation in HRV(L) was observed during repetitive appearances of apnea/hypopnea in the nocturnal experiments. CONCLUSION: The modified TIP together with HRV provides a superior tool for accurate and convenient definition of sleep apnea syndromes.