Chien-Ming Yang

Treatment Effects of Gabapentin for Primary Insomnia

Objectives:The prevalence of insomnia is very high in our society. Although pharmacological treatment of insomnia is available, most hypnotics have been shown to alter sleep architecture and have many adverse effects. Gabapentin was originally designed for antiepileptic therapy; however, some studies reported that its use increases slow-wave sleep in healthy volunteers or patients. Our goal was to evaluate the benefits of gabapentin in the treatment of primary insomnia in patients. Methods:Eighteen patients with primary insomnia participated in the study. They received gabapentin treatment for at least 4 weeks. All patients received polysomnography, a biochemical blood test, and neuropsychological tests before and after the treatment period. All measures were analyzed with Student t test to examine the treatment effects of gabapentin, except that the measures of heart rate variability were analyzed with analysis of variance. Results:Polysomnographic study revealed increased sleep efficiency and slow-wave sleep, decreased wake after sleep onset, and spontaneous arousal index after gabapentin treatment. The biochemical blood test revealed decreased prolactin levels in the morning after treatment. Electroencephalographic power spectral analysis showed increased delta-2 and theta power in sleep stage 1 and decreased sigma activity power in sleep stages N2 and N3 after gabapentin treatment. Heart rate variability analyses also showed a significant increase in normalized high frequency percentage in sleep stages N2 and N3 and low frequency-high frequency ratio in sleep stage N2 after treatment. In addition, neuropsychological tests revealed the elevation of visual motor processing speed after gabapentin treatment. Conclusions:Gabapentin enhances slow-wave sleep in patients with primary insomnia. It also improves sleep quality by elevating sleep efficiency and decreasing spontaneous arousal. The results suggest that gabapentin may be beneficial in the treatment of primary insomnia.

Automatic change detection: Does the auditory system use representations of individual stimulus features or gestalts?

The effects of global and feature-specific probabilities of auditory stimuli were manipulated to determine their effects on the mismatch negativity (MMN) of the human event-related potential. The question of interest was whether the automatic comparison of stimuli indexed by the MMN was performed on representations of individual stimulus features or on gestalt representations of their combined attributes. The design of the study was such that both feature and gestalt representations could have been available to the comparator mechanism generating the MMN. The data were consistent with the interpretation that the MMN was generated following an analysis of stimulus features.

Evidence for a new conceptualization of semantic representation in the left and right cerebral hemispheres

Two experiments are reported that examined qualitative differences in how semantic information is represented in the two hemispheres. In the first experiment, items that were associatively related but did not share semantic features or membership in semantic categories produced priming when delivered to the LH (RVF) but not to the RH (LVF). In the second experiment items that shared semantic features but were neither associates nor in the same category produced priming in the RH (LVF), but not in the LH (RVF). Together, the two experiments support the theory that, in the right hemisphere, semantic memories are represented within a distributed system, on the basis of semantic features, whereas, in the left hemisphere representations are, as in local models, relatively more holistic, and are connected via associative links.

Intracerebral hemodynamics probed by near infrared spectroscopy in the transition between wakefulness and sleep

Previous imaging studies have shown that cerebral metabolism is gradually reduced at the beginning of sleep. Few studies have examined the sleep state transition periods from wakefulness to sleep and sleep to wakefulness. The current study used the Near Infrared Spectroscopy (NIRS) technique to describe the intracerebral hemodynamics at the frontal pole in the circumscribed period between wakefulness and sleep. Nine healthy young adults were studied during afternoon naps. Optical probes were placed on the forehead and EEG electrodes on the scalp. At sleep onset oxygenated hemoglobin (oxy-Hb) was reduced (P<0.01) and deoxygenated hemoglobin (deoxy-Hb) showed a near significant reduction (P<0.063). At sleep offset there were increases in oxy-Hb (P<0.005) and deoxy-Hb (P<0.05). In 18 of 26 transitions to sleep there was a coordinated fall in both NIRS parameters, we call the Switch Point, that lasted a mean of 3.6 s. In 32 of 36 transitions to wakefulness there was an analogous Switch Point that lasted a mean of 3.4 s. Before and after the Switch Point, changes were small and the relationship between oxy-Hb and deoxy-Hb was a combination of parallel and reciprocal fluctuations. A synchronized, parallel and short-lived change in oxy-Hb and deoxy-Hb is a discrete event in the transition period between wakefulness and sleep. The concentration of these light absorbing molecules is abruptly set to a new level at sleep-wake transitions and probably reflects the different perfusion demands of these states.

Maladaptive sleep hygiene practices in good sleepers and patients with insomnia.

Previous studies examining the associations between sleep hygiene practices and insomnia have produced inconsistent results. This study further investigates this issue by examining different domains of sleep hygiene separately. One hundred and six insomnia patients and 89 good sleepers participated in the study. Their sleep hygiene, sleep quality and insomnia severity were assessed with subjective rating scales. Among good sleepers, almost all domains of sleep hygiene correlated significantly with their sleep ratings. However, in insomnia patients, only the arousal-related behavior correlated with sleep ratings. The findings suggest that strategies in prevention and treatment of sleep disturbance may be different accordingly.

The situational fatigue scale: a different approach to measuring fatigue.

Fatigue can be defined as a subjective state of an imbalance in the availability of inner resources needed to perform physical or mental activities. The level of fatigue is determined not only by the availability of inner resources but also by the demands of the activities performed. Most conventional fatigue scales require subjects to rate their level of fatigue without specifying the situation. In the present study, we constructed a subjective rating scale, the Situational Fatigue Scale (SFS), with which subjects estimated their level of fatigue in specific activities of daily life. We administered the SFS, along with the Fatigue Assessment Instrument (FAI) to 96 outpatients in a family-medicine clinic and to 62 college students to assess the psychometric properties of the SFS. Principle component analysis revealed two underlying factors: physical fatigue and mental fatigue. SFS scores were significantly correlated with several FAI scores and differentiated patients complaining of fatigue from those who did not. The SFS also showed good internal consistency and test–retest reliability. These results suggest that the SFS could be a useful tool to measure a different dimension of the broad concept of fatigue.

Clinical utility of the Chinese version of the Pediatric Daytime Sleepiness Scale in children with obstructive sleep apnea syndrome and narcolepsy.

Aim:  The present study examined the psychometric properties of the Chinese version of the Pediatric Daytime Sleepiness Scale (PDSS) and the utility of the PDSS as a screening tool for pathological daytime sleepiness in teenagers with obstructive sleep apnea (OSA) and narcolepsy.

The Association of Dysfunctional Beliefs About Sleep With Vulnerability to Stress-Related Sleep Disturbance in Young Adults

This study aims to explore the association between dysfunctional sleep beliefs and vulnerability to stress-related transient sleep disturbance in people without sleep disturbance. One hundred thirty-two good sleepers and 307 poor sleepers were included in this study. As expected, poor sleepers showed more dysfunctional beliefs than good sleepers on the Dysfunctional Beliefs and Attitudes about Sleep scale–10 item version (DBAS–10). More important, even in good sleepers, DBAS–10 scores positively correlated with the vulnerability to stress-related sleep disturbance as measured by the Ford Insomnia Response to Stress Test. The results suggest that dysfunctional sleep belief is not only a perpetuating factor for chronic insomnia, it may also serve as a risk factor for stress-related transient insomnia.

What subjective experiences determine the perception of falling asleep during sleep onset period

Sleep onset is associated with marked changes in behavioral, physiological, and subjective phenomena. In daily life though subjective experience is the main criterion in terms of which we identify it. But very few studies have focused on these experiences. This study seeks to identify the subjective variables that reflect sleep onset. Twenty young subjects took an afternoon nap in the laboratory while polysomnographic recordings were made. They were awakened four times in order to assess subjective experiences that correlate with the (1) appearance of slow eye movement, (2) initiation of stage 1 sleep, (3) initiation of stage 2 sleep, and (4) 5 min after the start of stage 2 sleep. A logistic regression identified control over and logic of thought as the two variables that predict the perception of having fallen asleep. For sleep perception, these two variables accurately classified 91.7% of the cases; for the waking state, 84.1%.

Comorbidity and confounding factors in attention-deficit/hyperactivity disorder and sleep disorders in children

Sleep problems are commonly reported in children with attention-deficit/hyperactivity disorder (ADHD) symptoms. Research data regarding the complex and reciprocal relationship between ADHD and sleep disturbances has now accumulated. This paper is focused on the types of sleep problems that are associated with ADHD symptomatology, and attempts to untangle confounding factors and overlapping symptoms. The goal is also to present an updated overview of the pathophysiology of and treatment strategies for sleep problems in children with ADHD. The review also points out that future research will be needed to clarify further the other psychiatric comorbidities and side effects of medication in order to improve treatment outcomes and prevent misdiagnosis in clinical practice.