Sustained wakefulness and visual attention: moderation by chronotype

Introduction - Attentional networks are sensitive to sleep deprivation and increased time awake. However, existing evidence is inconsistent and may be accounted for by differences in chronotype or time-of-day. We examined the effects of sustained wakefulness over a normal “socially constrained” day (following 18 h of sustained wakefulness), following a night of normal sleep, on visual attention as a function of chronotype. Methods - Twenty-six good sleepers (mean age 25.58; SD 4.26; 54 % male) completed the Attention Network Test (ANT) at two time points (baseline at 8 am; following 18-h sustained wakefulness at 2 am). The ANT provided mean reaction times (RTs), error rates, and the efficiency of three attentional networks—alerting, orienting, and executive control/conflict. The Morningness–Eveningness Questionnaire measured chronotype. Results - Mean RTs were longer at time 2 compared to time 1 for those with increasing eveningness; the opposite was true for morningness. However, those with increasing morningness exhibited longer RT and made more errors, on incongruent trials at time 2 relative to those with increasing eveningness. There were no significant main effects of time or chronotype (or interactions) on attentional network scores. Conclusion - Sustained wakefulness produced differential effects on visual attention as a function of chronotype. Whilst overall our results point to an asynchrony effect, this effect was moderated by flanker type. Participants with increasing eveningness outperformed those with increasing morningness on incongruent trials at time 2. The preservation of executive control in evening-types following sustained wakefulness is likely driven by differences in circadian phase between chronotypes across the day

Sleep Deprivation And Recovery: The Effects Of P300 Three And Six Hours Post Recovery

The P300 waveform is an auditory evoked potential (AEP) elicited through a decision making process. Due to the endogenous nature of the P300 response, which requires participants to actively respond to an auditory stimuli, it has been used as on objective measure to evaluate the cognitive processes of attention and memory. Previous studies have looked at the P300 before and after sleep deprivation as well as after brief rest periods. Evidence shows that a decline in P300 amplitudes and increase in latency are seen after 24 hours of sleep deprivation and improvements in the P300 are seen after a recovery period. Limited research has been conducted on the effects on P300 amplitude and latency during post recovery periods of three or more hours. The present study was designed to determine the effects of P300 three and six hours post recovery using an oddball paradigm (standard = 1000 Hz; target = 2000 Hz). AEPs were recorded for five conditions: baseline, sleep deprived, 110 minute recovery, three hours post recovery and six hours post recovery. Measures of P300 amplitude and latency were taken from Fz, Cz and Pz electrode sites. Peak to base amplitude and peak to peak amplitude of the P300 were also measured. Fourteen college and university students ages 18-25 were included in this study. Results indicated a significant decrease in P300 amplitude from the six hour post recovery condition compared to the baseline (p \u3c .05) as well as the six hour post recovery condition and sleep deprived condition (p \u3c .05). There were no significant changes in P300 latency across conditions. The results suggest that three to six hours after a brief recovery period of 110 minutes, cognitive decline is exacerbated

Proteomic changes in rat hippocampus and adrenals following short-term sleep deprivation

ABSTRACT: BACKGROUND: To identify the biochemical changes induced by sleep deprivation at a proteomic level, we compared the hippocampal proteome of rats either after 4 hours of sleep or sleep deprivation obtained by gentle handling. Because sleep deprivation might induce some stress, we also analyzed proteomic changes in rat adrenals in the same conditions. After sleep deprivation, proteins from both tissues were extracted and subjected to 2D-DIGE analysis followed by protein identification through mass spectrometry and database search. RESULTS: In the hippocampus, 87 spots showed significant variation between sleep and sleep deprivation, with more proteins showing higher abundance in the latter case. Of these, 16 proteins were present in sufficient amount for a sequencing attempt and among the 12 identified proteins, inferred affected cellular functions include cell metabolism, energy pathways, transport and vesicle trafficking, cytoskeleton and protein processing. Although we did not observe classical, macroscopic effect of stress in sleep-deprived rats, 47 protein spots showed significant variation in adrenal tissue between sleep and sleep deprivation, with more proteins showing higher abundance following sleep. Of these, 16 proteins were also present in sufficient amount for a sequencing attempt and among the 13 identified proteins, the most relevant cellular function that was affected was cell metabolism. CONCLUSION: At a proteomic level, short term sleep deprivation is characterized by a higher expression of some proteins in the hippocampus and a lower abundance of other proteins in the adrenals (compared to normal sleep control). Altogether, this could indicate a general activation of a number of cellular mechanisms involved in the maintenance of wakefulness and in increased energy expenditure during sleep deprivation. These findings are relevant to suggested functions of sleep like energy repletion and the restoration of molecular stocks or a more global homeostasis of synaptic processes

Extended Remediation of Sleep Deprived-Induced Working Memory Deficits Using fMRI-Guided Transcranial Magnetic Stimulation

STUDY OBJECTIVES: We attempted to prevent the development of working memory (WM) impairments caused by sleep deprivation using fMRI-guided repetitive transcranial magnetic stimulation (rTMS). Novel aspects of our fMRI-guided rTMS paradigm included the use of sophisticated covariance methods to identify functional networks in imaging data, and the use of fMRI-targeted rTMS concurrent with task performance to modulate plasticity effects over a longer term. DESIGN: Between-groups mixed model. SETTING: TMS, MRI, and sleep laboratory study. PARTICIPANTS: 27 subjects (13 receiving Active rTMS, and 14 Sham) completed the sleep deprivation protocol, with another 21 (10 Active, 11 Sham) non-sleep deprived subjects run in a second experiment. INTERVENTIONS: Our previous covariance analysis had identified a network, including occipital cortex, which demonstrated individual differences in resilience to the deleterious effects of sleep deprivation on WM performance. Five Hz rTMS was applied to left lateral occipital cortex while subjects performed a WM task during 4 sessions over the course of 2 days of total sleep deprivation. MEASUREMENTS AND RESULTS: At the end of the sleep deprivation period, Sham sleep deprived subjects exhibited degraded performance in the WM task. In contrast, those receiving Active rTMS did not show the slowing and lapsing typical in sleep deprivation, and instead performed similarly to non- sleep deprived subjects. Importantly, the Active sleep deprivation group showed rTMS-induced facilitation of WM performance a full 18 hours after the last rTMS session. CONCLUSIONS: Over the course of sleep deprivation, these results indicate that rTMS applied concurrently with WM task performance affected neural circuitry involved in WM to prevent its full impact

Light, activity and sleep in my daily life: : Design of an online intervention targeting changes to routines and the home

Background: Older adults spend more time at home after retirement, and the home becomes a central place for activity. While research indicates that indoor lighting, exposure to daylight, physical activity and sleep interact to influence functioning, mood and daily rhythm, strategies are needed to promote behavioural changes to optimise these factors in daily life. The objective is to design an intervention delivered as a web-based course to encourage behaviour change related to outdoor physical activity, sleep patterns and changes to the home environment. The behaviour changes are intended to promote mental wellbeing and improve lighting and darkness conditions. The intervention strategy departs from the Information-Motivation-Behavioural Skills Model. Intervention components build on goal implementation theory. The Technology Acceptance Model is used as a framework to evaluate usability aspects of the course content and the learning management system. Method: Using a mixed-methods approach, qualitative and quantitative data were collected through video observations, semi-structured interviews and a 10-item Likert scale questionnaire (The System Usability Scale). Scores were averaged for each participant and converted into a usability score out of 100 (a score of 68 or above is considered above average). In a first round, three experts on pedagogy, design for older people and/or interaction design were invited to independently assess the usability of the course content on their laptops in a full-scale model of an apartment. The setting enabled manipulations of the lighting conditions (daylight mode and night mode, change of luminaires), contextual interviews and video observation to identify any problems when participants experimented with the test kit included in the course material. They participated on three occasions lasting 2 hours each. Six healthy adults (aged 70+) participated in a similar usability trial in a second round. Findings: Experts’ average usability score was 78.3, indicating “Good” usability. However, the interviews did reveal some issues (e.g. difficult or inconsistent terms, unclear instructions). Results were used to refine the course before the second usability trial with six participants. Based on the interviews and usability ratings, the participants were positive about the course, and the instructions were easy to follow. All six participants rated the overall user-friendliness of the course as 6 out of 7. The average usability score was 86.7, indicating “Excellent” usability. Based on the participants’ feedback and interactions in the apartment, changes to the course content included, e.g. clarifying terms, the different types of text links and instructions. Unexpected issues with online enrolment in the course appeared before the second trial because standard instructions developed by the university were not tailored to the participants.Conclusions: A two-step usability evaluation by experts in the first round and target users in the second proved valuable. It enabled refinement of the course content and significantly reduced the number of identified usability issues in the second trial. A learning management system seems promising for use in behaviour-change interventions. However, the time-limited lab trials restricted a complete evaluation. Therefore, the next step is to pilot the course and evaluate the feasibility in real-world homes

Usage of daylight in the built environment:impact on health

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Cognitive correlates of sleepiness and sleep disruption in everyday domestic settings

Sleepiness and sleep disruption caused by cohabitees could have deleterious cognitive consequences in everyday life. Research in this area is scarce, thus cognitive correlates of varying degrees of sub-optimal sleep patterns in five groups of healthy adults in domestic settings were studied. The groups studied included adults living with healthy partners, adults living with partners with a chronic, sleep-disrupting illness (Parkinson's disease), and mothers of young children

EPFL Smart Glass Field Study

The objectives of this study are to evaluate (1) direct non-visual effects of red-impoverished daylight on circadian resetting and alertness and (2) the daily light-exposure pattern on indirect–circadian–effects. The novelty of this study is that it will be conducted on the EPFL campus in two identical classrooms outfitted with electrochromic windows from SageGlass. Studying non-visual effects under real-life conditions are essential to better understand the role of an adaptive glazing to improve alertness in the context of a classroom. We will also log irradiance and illuminance at eye level in order to document light received at the eye over two 6-day trials. We hope that recording light exposure during wake hours will help us to better understand the type of light people receive on a daily basis and if adaptive glazing technologies can help mitigate negative physiological responses normal working hours