Melatonin rhythm abnormalities and sleep disorders in the elderly

Biological aging is often associated with sleep problems and daytime napping. Complaints of difficulty in initiating and maintaining sleep, as well as daytime drowsiness, are more common in the elderly than in any other age group. This report reviews evidence that impaired melatonin secretion is associated with sleep disorders in old age. Circulating melatonin levels have been found to be significantly lower and onset and peak times have been delayed in elderly insomniacs as compared to age-matched control subjects. In view of these findings, we investigated the effects of melatonin treatment on melatonin-deficient insomnia in the elderly. From the results of our study, it seems likely that melatonin replacement therapy may be beneficial in the initiation and maintenance of sleep in this population.     

Circadian rhythm and performance during a 24-hour relay race

The performance of two participating teams (ns = 18) in a 24-hr. relay race was analysed. The performance of both teams showed a clear decline during the course of the competition; however, the expected circadian variation of performance could only be found for one team. This finding may be attributable to the different levels of fitness of the two teams. Considerable interindividual differences were found with regards to the course of performance.     

Boredom proneness and sleep disorders as predictors of adult attention deficit scores

This study examined the extent to which boredom proneness and sleep disturbances were related to attention deficit scores in college-aged adults. In a sample of 148 college students, Attention scores on the Adult Behavior Checklist were best predicted by Boredom Proneness (BP) subscale scores, which assess one's inability to maintain internal stimulation and feelings of constraint, and scores on the Epworth Daytime Sleepiness Scale and Athens Insomnia Scale (R2 = .57). Hyperactivity scores were best predicted by the BP subscales, which assess one's need for a stimulating environment, the perception of time passing slowly, and feelings of constraint, and the Epworth Scale (R2 = .51). The findings contribute to the understanding of the symptomatology of attention deficit in adults and provide further evidence of the validity of this measure.     

A review of mentation in REM and NREM sleep: "covert" REM sleep as a possible reconciliation of two opposing models

Numerous studies have replicated the finding of mentation in both rapid eye movement (REM) and nonrapid eye movement (NREM) sleep. However, two different theoretical models have been proposed to account for this finding: (1) a one-generator model, in which mentation is generated by a single set of processes regardless of physiological differences between REM and NREM sleep; and (2) a two-generator model, in which qualitatively different generators produce cognitive activity in the two states. First, research is reviewed demonstrating conclusively that mentation can occur in NREM sleep; global estimates show an average mentation recall rate of about 50% from NREM sleep--a value that has increased substantially over the years. Second, nine different types of research on REM and NREM cognitive activity are examined for evidence supporting or refuting the two models. The evidence largely, but not completely, favors the two-generator model. Finally, in a preliminary attempt to reconcile the two models, an alternative model is proposed that assumes the existence of covert REM sleep processes during NREM sleep. Such covert activity may be responsible for much of the dreamlike cognitive activity occurring in NREM sleep.     

Increased theft as a side effect of sales promotion activities: An exploratory study

A combination of commonly used promotional activities, i.e., advertising, price reductions and increased exposure, was associated with increased thefts of six candy products. Thefts increased for each of the six products during the period the combination of promotional activities was used. Large increases in sales were observed for only two of the products. Sales of the other four products increased marginally or decreased in conjunction with promotional activities. When compared to normal sales conditions, the period of promotional activities produced less net profit per week for five of the six products. The results are of interest to retailers since they indicate that promotional activities for some products may produce a negative side effect, namely, increased theft. Further, promotional activities may not always produce increased sales.     

A review of common sleep disorders

What should clinicians know about sleep disorders? This article briefly introduces the reader to sleep medicine and succinctly reviews common sleep disorders. First, the authors describe the diagnostic tools unique to sleep medicine: the over-night polysomnogram and the multiple sleep latency test. Next, the authors review essential features of a subset of the sleep, described in the International Classification of Sleep Disorders-Revised, that sleep disorder specialists commonly evaluate, diagnose, and treat. The disorders reviewed include the intrinsic and circadian rhythm subsets of the dyssomnias group and the parasomnia group of sleep disorders. The authors identify the core signs and symptoms, polysomnogram findings, multiple sleep latency test findings, and treatment of these disorders.     

Fluency and positivity as possible causes of the truth effect

Statements’ rated truth increases when people encounter them repeatedly. Processing fluency is a central variable to explain this truth effect. However, people experience processing fluency positively, and these positive experiences might cause the truth effect. Three studies investigated positivity and fluency influences on the truth effect. Study 1 found correlations between elicited positive feelings and rated truth. Study 2 replicated the repetition-based truth effect, but positivity did not influence the effect. Study 3 conveyed positive and negative correlations between positivity and truth in a learning phase. We again replicated the truth effect, but positivity only influenced judgments for easy statements in the learning phase. Thus, across three studies, we found positivity effects on rated truth, but not on the repetition-based truth effect: We conclude that positivity does not explain the standard truth effect, but the role of positive experiences for truth judgments deserves further investigation.     

The effect of a delayed weekend sleep pattern on sleep and morning functioning

Abstract

It is a common practice for young adults to delay their weekend sleep schedule. The present study was designed to assess the effect of this sleep pattern on the sleep of Sunday night and the functioning of Monday morning. The sleep schedules of 30 young adults were manipulated for 2 consecutive weeks. In the Habitual-Sleep (HS) week, subjects followed their habitual sleep schedule throughout the week; in the Delayed-Sleep (DS) week, subjects' sleep schedule on Friday and Saturday nights were delayed by two hours. Compared to the HS week, subjects showed significantly lower subjective sleepiness near bedtime and trends of longer sleep onset latency on Sunday night in the DS week. In addition, there was both lowered cognitive performance and overall mood rating on Monday morning in the DS week. The delayed weekend sleep pattern contributes to Sunday night insomnia and the Monday morning “blues”.     

Auditory lateralization: An effect of rhythm

Recall of monaurally presented semantically anomalous sentences, which had either neutral or rhythmic timing, was tested at the right ear, at the left ear, and on transfer from one ear to the other. The component words, being computer stored digitized waveforms, had identical acoustic structure in the two conditions. In the rhythmic condition there was not only an overall advantage in the second half of the experiment but also an asymmetric transfer effect such that this advantage did not appear when the left ear was tested after the right. It is proposed that functional lateralization be viewed as an adaptive, dynamic, organizational factor.     

Re-evaluation of a possible proximity effect on muscular strength

Inconsistent findings of a proximity effect of sucrose on muscular strength and a potential interaction of nutritional status prompted the current study. Double-blind, counterbalanced assessments of grip strength were performed with and without 76 subjects holding a container of sucrose. No main effect was found for proximity of glucose, and no interaction was found for prandial status.     

Sick-building syndrome fatigue as a possible predation defense

Sick-building syndrome is an illness characterized by fatigue, headache, and upper-respiratory complaints. It is usually associated with modern office buildings, structures with an impervious outer shell and inoperable windows. Poor air quality, specific pollutants, and inadequate ventilation are considered common causes. The ability to smell faint odors requires air that is free of contamination. Human evolutionary ancestors depended on odors for survival. Even the slightest increase in the ability to smell a predator conveyed a distinct, immediate survival advantage. Conversely, an enormous survival advantage would also accrue to the animal that sought protection or avoided activity when this vital olfactory information was unavailable. Such would be the case with fire on the savannah. The foraging, olfactory dependent animal, unable to smell predators because of contaminated air, would be quickly snatched by a keen-sighted carnivore. There exist, however, well-described reflexes from the nose mediated through the trigeminal nerve that discourage activity when these free nerve endings are irritated. This mechanism may serve as a defense against predation. In adulterated atmosphere the animal, subdued by these reflexes, would be less likely to venture forth and, therefore, less vulnerable to predators. Similar reflexes may persist in humans, activated by poor air quality, air ill-suited for the dissemination of odors. I suggest that the human perception of these inhibitory reflexes is the feeling of fatigue associated with the sick building syndrome.