Sleep, Health, and Aging

As people grow older, getting a good night's sleep remains essential to maintaining good health. Insomnia is a common complaint in older adults, and although occasional sleep complaints may not be associated with age, chronic sleep difficulties are experienced more often by older adults than by younger adults

Sleep deprivation impairs object-selective attention: A view from the ventral visual cortex

10.1371/journal.pone.0009087PLoS ONE52

Attention in the Brain Under Conditions of Sub-Optimal Alertness: Neurobiological Effects and Individual Differences

Sleep deprivation (SD) is a prevalent problem in modern society, and one that can have serious adverse consequences for health and safety. Critically, even short periods of SD can lead to relatively large decrements in attention, which may in turn cause an individual to neglect important environmental stimuli. In this thesis, I report the results of three experiments designed to investigate the neural bases of attentional declines under conditions of sleep loss and mental fatigue. In two experiments using arterial spin labeled fMRI, a technique that enables the quantification of absolute levels of cerebral blood flow (CBF), it was found that CBF patterns in the resting brain differed significantly based on arousal levels (Study #1) and prior cognitive workload (Study #2). These findings are a departure from prior neuroimaging studies, which have typically taken neural activity during non-task periods as static and inseparable baseline. In a test of sustained attention, performance declines were observed both following SD (Study #1) and when performing the task for an extended period of time while well-rested (Study #2). These decrements were primarily mediated by hypoactivation in a fronto-parietal attentional circuit. Furthermore, resting baseline levels of cerebral blood flow in the thalamus and prefrontal cortex before the start of the task were predictive of interindividual differences in subsequent performance decline (Study #2). In Study #3, an experiment using standard BOLD fMRI, it was found that performance declines in a test of selective attention following SD were accompanied by reduced functional connectivity between top-down control areas and regions of ventral visual cortex, as well as reductions in activation to targets in object-selective areas. Taken together, these results further our understanding of the neural basis of attention under conditions when this system is taxed beyond its normal limits

Glucose as a Mediator of the Relationship Between Sleep and Cognitive Performance

ABSTRACT The Centers for Disease Control and Prevention (Y. Liu et al., 2016) reports that 34.8% of adults living in the United States of America are getting less than their recommended amount of sleep per night. Additionally, the National Sleep Foundation (2014) reports that 35% of adults have poor sleep quality. Sleep problems appear most prevalent in young adults (Hershner, 2015). Rates of type 2 diabetes mellitus are also on the rise in this specific population (Kaufman, 2002). Interestingly, research has consistently found that both sleep quantity and quality are associated with glucose levels (Ip & Mokhlesi, 2007; Padilha et al., 2011; Taub & Redeker, 2008). Further, both sleep quantity and quality, as well as glucose, can have a significant effect on cognitive performance (Alhola & Polo-Kantola, 2007; Zilliox et al., 2016). The purpose of the present study was to investigate the mediating effect of glucose on the relationship between sleep and cognitive performance. Sleep included sleep quantity and quality. Cognitive performance included both sustained attention and visuospatial working memory. It was predicted that sleep would be positively related to cognitive performance, and negatively related to glucose levels. It was also predicted that glucose levels, even in a prediabetic range, would be negatively related to cognitive performance, and that this would mediate the relationship between sleep and cognitive performance. To test these hypotheses, data were collected from 82 young adults. Participants answered demographic questionnaires, and surveys assessing their sleep quantity and quality. They then had their glucose levels assessed via finger-stick glucose monitoring. Following this, they completed computerized tasks measuring sustained attention and visuospatial working memory. A hierarchical multiple regression analysis was conducted to test the proposed hypotheses. After cleaning, 81 cases were found to be viable for analysis. Results obtained were in partial support of hypotheses. Poor sleep quality, as measured by the Adult Sleep-Wake Scale (ADSWS; Fortunato et al., 2008), was found to be associated with decreased visuospatial working memory (β = -.02, p = .039). No other hypotheses were supported, though some trending results were found. It is believed had a larger and/or more diverse sample been used, more significant results would have been found. Implications exist not only for students, but for all young adults. They are likely to be of interest to young adults, as well as those working with young adults. This includes mental health professionals, various medical personnel, teachers, and school administrators

Social interactions, emotion and sleep: a systematic review and research agenda

Sleep and emotion are closely linked, however the effects of sleep on socio-emotional task performance have only recently been investigated. Sleep loss and insomnia have been found to affect emotional reactivity and social functioning, although results, taken together, are somewhat contradictory. Here we review this advancing literature, aiming to 1) systematically review the relevant literature on sleep and socio-emotional functioning, with reference to the extant literature on emotion and social interactions, 2) summarize results and outline ways in which emotion, social interactions, and sleep may interact, and 3) suggest key limitations and future directions for this field. From the reviewed literature, sleep deprivation is associated with diminished emotional expressivity and impaired emotion recognition, and this has particular relevance for social interactions. Sleep deprivation also increases emotional reactivity; results which are most apparent with neuro-imaging studies investigating amygdala activity and its prefrontal regulation. Evidence of emotional dysregulation in insomnia and poor sleep has also been reported. In general, limitations of this literature include how performance measures are linked to self-reports, and how results are linked to socio-emotional functioning. We conclude by suggesting some possible future directions for this field

FMRI Study of Effects of Sleep Deprivation on Attentional Capacity

Ph.DDOCTOR OF PHILOSOPH

Sleepiness, Safety and Transport

The economic development of modern society requires continuous improvement of transport and their efficiency throughout the span of 24 hours. Drowsiness may be a serious risk to the safety of employees, passengers and third parties. Sleepiness at the wheel is responsible for 5% to 30% of road accidents. Several pathophysiological factors governing the driving skills were studied: lifestyles, work schedules, prolonged wakefulness, stress, and sleep disorders. Screening of sleep disorders and education of workers at a proper sleep hygiene are fundamental keys to the safe transport. The individual initiatives to reduce the risk of drowsiness should be framed in a more general safety effort of the institutions

Effects of circadian rhythm phase alteration on physiological and psychological variables: Implications to pilot performance (including a partially annotated bibliography)

The effects of environmental synchronizers upon circadian rhythmic stability in man and the deleterious alterations in performance and which result from changes in this stability are points of interest in a review of selected literature published between 1972 and 1980. A total of 2,084 references relevant to pilot performance and circadian phase alteration are cited and arranged in the following categories: (1) human performance, with focus on the effects of sleep loss or disturbance and fatigue; (2) phase shift in which ground based light/dark alteration and transmeridian flight studies are discussed; (3) shiftwork; (4)internal desynchronization which includes the effect of evironmental factors on rhythmic stability, and of rhythm disturbances on sleep and psychopathology; (5) chronotherapy, the application of methods to ameliorate desynchronization symptomatology; and (6) biorythm theory, in which the birthdate based biorythm method for predicting aircraft accident susceptability is critically analyzed. Annotations are provided for most citations

Cognitive enhancement effects of stimulants: a randomized controlled trial testing methylphenidate, modafinil, and caffeine

Rational: At all times humans have made attempts to improve their cognitive abilities by different means, among others, with the use of stimulants. Widely available stimulants such as caffeine, but also prescription substances such as methylphenidate and modafinil, are being used by healthy individuals to enhance cognitive performance. Objectives: There is a lack of knowledge on the effects of prescription stimulants when taken by healthy individuals (as compared with patients) and especially on the effects of different substances across different cognitive domains. Methods: We conducted a pilot study with three arms in which male participants received placebo and one of three stimulants (caffeine, methylphenidate, modafinil) and assessed cognitive performance with a test battery that captures various cognitive domains. Results: Our study showed some moderate effects of the three stimulants tested. Methylphenidate had positive effects on self-reported fatigue as well as on declarative memory 24 hours after learning; caffeine had a positive effect on sustained attention; there was no significant effect of modafinil in any of the instruments of our test battery. All stimulants were well tolerated, and no trade-off negative effects on other cognitive domains were found. Conclusions: The few observed significant positive effects of the tested stimulants were domain-specific and of rather low magnitude. The results can inform the use of stimulants for cognitive enhancement purposes as well as direct further research to investigate the effects of stimulants on specific cognitive domains that seem most promising, possibly by using tasks that are more demanding