Sleep during a regular week night: a twin-sibling study.

Previous genetic investigations of variation in normal sleep have focused on measures that describe sleep over longer periods of time. We undertook a study with the aim of evaluating whether heritability can be found in single-night sleep traits. A classical twin study design of monozygotic and dizygotic twins, enriched with siblings of twins was employed.

Diminished capability to recognize the optimal temperature for sleep initiation may contribute to poor sleep in elderly people.

Study Objectives: Sleep propensity and skin temperature are functionally related. In young adults, changes of skin temperature within the comfortable thermoneutral zone affect sleep-onset latency and vigilance performance. Aging is associated with both decreased thermosensitivity and poorer sleep.

Prefrontal hypoactivation and recovery in insomnia.

Study Objectives: Although subjective complaints about daytime cognitive functioning are an essential symptom of chronic insomnia, abnormalities in functional brain activation have not previously been investigated. This study was designed to investigate functional brain activation differences as a possible result of chronic insomnia, and the reversibility of these differences after nonmedicated sleep therapy.

Design: Insomniacs and carefully matched controls underwent functional magnetic resonance imaging (fMRI) scanning during the performance of a category and a letter fluency task.

Clinical update: melatonin and sleep disorders.

The hormone melatonin is increasingly used for the treatment of certain sleep disorders, particularly those related to disturbed biological rhythms. This article summarises current knowledge of its mechanism of action and identifies situations where there is good evidence for its efficacy. The authors provide advice, based on their own experience and consistent published data, concerning the dose range of melatonin to be used and the critically important question of the timing of treatment.

Bright light in elderly subjects with nonseasonal major depressive disorder: a double blind randomised clinical trial using early morning bright blue light comparing dim red light treatment.

Background: Depression frequently occurs in the elderly. Its cause is largely unknown, but several studies point to disturbances of biological rhythmicity. In both normal aging, and depression, the functioning of the suprachiasmatic nucleus (SCN) is impaired, as evidenced by an increased prevalence of day-night rhythm perturbations, such as sleeping disorders.

Manipulation of skin temperature improves nocturnal sleep in narcolepsy.

Objective: Besides excessive daytime sleepiness, disturbed nocturnal sleep is a major complaint of patients with narcolepsy. Previously, alterations in skin temperature regulation in narcoleptic patients have been shown to be related to increased sleepiness. This study tests the hypothesis that direct control of nocturnal skin temperature might be applied to improve the disturbed sleep of narcoleptic patients.

The relationship between insomnia and body temperatures.

Sleepiness and sleep propensity are strongly influenced by our circadian clock as indicated by many circadian rhythms, most commonly by that of core body temperature. Sleep is most conducive in the temperature minimum phase, but is inhibited in a "wake maintenance zone" before the minimum phase, and is disrupted in a zone following that phase. Different types of insomnia symptoms have been associated with abnormalities of the body temperature rhythm.

Insomnia on dialysis nights: the beneficial effects of cool dialysate.

Background: Hemodialysis (HD) induces physiological changes that may affect the ability to dissipate heat and adversely affect sleep on the nights following treatment. We studied the effects of altering dialysate temperature on polysomnographic measures of nocturnal sleep and the time course of proximal skin temperature.

Methods: The sample included seven stable HD patients.

Effect of bright light and melatonin on cognitive and noncognitive function in elderly residents of group care facilities: a randomized controlled trial.

Context: Cognitive decline, mood, behavioral and sleep disturbances, and limitations of activities of daily living commonly burden elderly patients with dementia and their caregivers. Circadian rhythm disturbances have been associated with these symptoms.

Objective: To determine whether the progression of cognitive and noncognitive symptoms may be ameliorated by individual or combined long-term application of the 2 major synchronizers of the circadian timing system: bright light and melatonin.

Low-frequency stimulation induces stable transitions in stereotypical activity in cortical networks.

Reverberating spontaneous synchronized brain activity is believed to play an important role in neural information processing. Whether and how external stimuli can influence this spontaneous activity is poorly understood. Because periodic synchronized network activity is also prominent in in vitro neuronal cultures, we used cortical cultures grown on multielectrode arrays to examine how spontaneous activity is affected by external stimuli.

Manipulation of core body and skin temperature improves vigilance and maintenance of wakefulness in narcolepsy.

Context: Impaired vigilance and sleepiness are two majordaily complaints of patients with narcolepsy. We previously showed their sleepiness to be correlated to an abnormally regulated skin temperature, i.e.

Skin deep: enhanced sleep depth by cutaneous temperature manipulation.

With ageing, an increasingly disturbed sleep is reported as a significant complaint affecting the health and well-being of many people. The available treatments for sleep disturbance have their limitations, so we have adopted a different approach to the improvement of sleep. Since in animal and human studies skin warming has been found to increase neuronal activity in brain areas that are critically involved in sleep regulation, we investigated whether subtle skin temperature manipulations could improve human sleep.

Melatonin and bright-light treatment for rest-activity disruption in institutionalized patients with Alzheimer's disease.

Objectives: To test whether the addition of melatonin to bright-light therapy enhances the efficacy in treating rest-activity (circadian) disruption in institutionalized patients with Alzheimer's disease (AD).

Design: Randomized, controlled trial.

Setting: Two nursing homes in San Francisco, California.

Live to the rhythm, slave to the rhythm.

Circadian rhythms in health and disease have most often been described in terms of their phases and amplitudes, and how these respond to a single exposure to stimuli denoted as zeitgebers. The present paper argues that it is also important to consider the 24-h regularity in the repeated occurrence of the zeitgebers. The effect of the regularity of stimulation by light, melatonin, physical activity, body temperature, corticosteroids and feeding on synchronization within and between the central circadian clock and peripheral oscillators is discussed.

Observations on the cortical silent period in Parkinson's disease.

Transcranial magnetic stimulation is a tool in the neurosciences to study motor functions and nervous disorders, amongst others. Single pulses of TMS applied over the primary motor cortex lead to a so-called cortical silent period in the recording from the corresponding muscle, i.e.

Attenuated effect of increased daylength on activity rhythm in the old mouse lemur, a non-human primate.

Adaptation of physiological and behavioral functions to seasonal changes in daylength is of major relevance for optimal fitness and survival. Because aging is characterized by changes in biological rhythms, it may be hypothesized that old animals fall short of showing a full adaptation to prolonged changes in the duration of daily light exposure, as naturally occurring in relation to season in younger individuals. To test this hypothesis, we analyzed changes in the patterns of daily locomotor activity and body temperature rhythms of young and old mouse lemurs (Microcebus murinus, Primates) exposed to short and long daylengths.

Integration of known transcription factor binding site information and gene expression data to advance from co-expression to co-regulation.

The common approach to find co-regulated genes is to cluster genes based on gene expression. However, due to the limited information present in any dataset, genes in the same cluster might be co-expressed but not necessarily co-regulated. In this paper, we propose to integrate known transcription factor binding site information and gene expression data into a single clustering scheme.

Improving actigraphic sleep estimates in insomnia and dementia: how many nights?

In order to investigate how the duration of actigraphic recordings affects the reliability of actigraphic estimates of sleep and 24-h activity rhythm variables, two to 3 weeks of actigraphy were recorded, from which pairs of variables derived from two periods of increasing length (1-10 days) were compared. Two groups were studied: (1) 10 subjects suffering from primary insomnia; and (2) 12 demented elderly subjects living semi-independently in group care facilities of homes for the elderly. Actigraphic estimates of primary measures of sleep (duration and efficiency) and of the 24-h activity pattern (interdaily stability, intradaily variability and amplitude) were calculated on variable lengths of the actigraphic recordings.

Hyperactive night and day? Actigraphy studies in adult ADHD: a baseline comparison and the effect of methylphenidate.

Study Objectives: To investigate parameters of sleep, activity, and circadian rhythm, as well as the effects of methylphenidate on these variables, in adults with ADHD.

Design: 1) Baseline group comparison; 2) Double blind, placebo-controlled, cross-over medication trial.

Setting: Data collection took place during daily lives of participants.

Improving melatonin circadian phase estimates.

The quality and quantity of sleep is to a large extent determined by whether the sleep period is in alignment with the most favorable circadian time window for sleep. Misalignment results in compromised sleep. In order to determine this circadian time window, the 24-h profile of melatonin secretion is generally considered to provide the most optimal estimate.

Estimating the effects of right median nerve stimulation on memory in Alzheimer's disease: a randomized controlled pilot study.

The goal of the present study was to examine possible effects of right median nerve stimulation (RMNS) on memory in patients in a relatively early stage of probable Alzheimer's disease (AD). Seventeen AD patients were randomly assigned to an experimental group (n = 8) and a control group (n = 9) and treated with RMNS and sham RMNS, respectively, for 30 min a day, 5 days a week, for 6 weeks. Neuropsychological tests were used to assess memory processes.

Time-on-task impairment of psychomotor vigilance is affected by mild skin warming and changes with aging and insomnia.

Study Objectives: To investigate the effect of mild manipulations of core and skin temperature on psychomotor vigilance (PVT) in young adults, elderly, and elderly insomniacs.

Design: 432 PVTs were obtained during a 2-day semi-constant routine protocol, while differentially manipulating core and skin temperatures within a comfortable thermoneutral range.

Setting: Sleep laboratory of the Netherlands Institute for Neuroscience.

Lowering dialysate temperature improves sleep and alters nocturnal skin temperature in patients on chronic hemodialysis.

Hemodialysis (HD) induces physiological changes that may affect the ability to dissipate heat and adversely affect sleep. We studied the effects of altering dialysate temperature on polysomnographic measures of nocturnal sleep and the time course of proximal skin temperature. The sample included seven stable HD patients.

Strong association of the rest-activity rhythm with well-being in demented elderly women.

Objective: The objective of this study is to investigate the association between actigraphic estimates of the sleep-wake rhythm and a range of functional domains that contribute to well-being in demented elderly patients.

Method: Eighty-seven women aged 85.5 +/- 5.