Thursday 24th November 2016 - Conference
Track 5: Human Health and Safety (Chair: Kirrilly Thompson)
Does sleep restriction impair glucose metabolism?
Keywords: Glucose metabolism, type 2 diabetes, blood sugar, sleep restriction, night time glucose metabolism
Author: Thomas Kontou
Affiliation: Central Queensland University
Email address: t.kontou@cqu.edu.au
Lay summary:
Glucose metabolism refers to how well the human body processes glucose which circulates in the blood. Impaired glucose tolerance is a hallmark of the disease Type 2 Diabetes. This research investigated glucose metabolism at night time in participants who were permitted six or eight hours time in bed per night for seven nights.
Abstract:
Restricting sleep duration to below six hours per night for consecutive nights results in impaired glucose tolerance during glucose challenge tests. However the influence of such sleep restriction on glucose metabolism during sleep is less well understood. A laboratory study was conducted to investigate the effect of multiple nights of sleep restriction on glucose metabolism during sleep.
Seven male participants lived in a sleep laboratory for eight nights. Participants had a nine-hour baseline sleep opportunity (2300h to 0800h) followed by either eight hours time in bed per night from 0000h to 0800h (N=3; mean age±SD: 20.3±4.0) or six hours time in bed per night from 0200h to 0800h (N=4, mean age±SD: 21.5±3.8). Interstitial glucose concentrations were measured continuously using glucose monitors.
For each participant, area under the curve was measured from 0200h to 0800h during the final sleep opportunity in each condition and expressed relative to baseline. Area under the curve for glucose concentrations was not different between the two groups [t(5) = -1.83, p = 0.125].
Restricting sleep from eight hours to six hours per night did not affect glucose concentrations during sleep. There are several possible explanations for this. First, the system for regulating glucose during sleep may be more robust than the system for regulating glucose concentrations during a glucose challenge administered in the day time. Second, reducing sleep opportunities to six hours per night may not be sufficient to impair glucose metabolism during sleep. Finally, at the time of abstract submission, the sample size of our group was small (seven participants) and may have reduced statistical power. At the time of the conference, this data set will have increased to 19 participants.
Glucose metabolism refers to how well the human body processes glucose which circulates in the blood. Impaired glucose tolerance is a hallmark of the disease Type 2 Diabetes. This research investigated glucose metabolism at night time in participants who were permitted six or eight hours time in bed per night for seven nights.
Abstract:
Restricting sleep duration to below six hours per night for consecutive nights results in impaired glucose tolerance during glucose challenge tests. However the influence of such sleep restriction on glucose metabolism during sleep is less well understood. A laboratory study was conducted to investigate the effect of multiple nights of sleep restriction on glucose metabolism during sleep.
Seven male participants lived in a sleep laboratory for eight nights. Participants had a nine-hour baseline sleep opportunity (2300h to 0800h) followed by either eight hours time in bed per night from 0000h to 0800h (N=3; mean age±SD: 20.3±4.0) or six hours time in bed per night from 0200h to 0800h (N=4, mean age±SD: 21.5±3.8). Interstitial glucose concentrations were measured continuously using glucose monitors.
For each participant, area under the curve was measured from 0200h to 0800h during the final sleep opportunity in each condition and expressed relative to baseline. Area under the curve for glucose concentrations was not different between the two groups [t(5) = -1.83, p = 0.125].
Restricting sleep from eight hours to six hours per night did not affect glucose concentrations during sleep. There are several possible explanations for this. First, the system for regulating glucose during sleep may be more robust than the system for regulating glucose concentrations during a glucose challenge administered in the day time. Second, reducing sleep opportunities to six hours per night may not be sufficient to impair glucose metabolism during sleep. Finally, at the time of abstract submission, the sample size of our group was small (seven participants) and may have reduced statistical power. At the time of the conference, this data set will have increased to 19 participants.
The predictive value of self-rated driving ability is dependent on sleep duration and time of day
Keywords: sleep, fatigue, self-ratings, driving, accidents
Author: Anastasi Kosmadopoulos
Affiliation: Appleton Institute, Central Queensland University
Email address: a.kosmadopoulos@cqu.edu.au
Lay summary:
Driving performance is worse when sleep restricted and worse at night. Self-ratings of ability can predict driving performance when fatigued at most times of day. As such, there is value in people self-report so appropriate responses can be made to mitigate risk.
Abstract:
Sophisticated technologies have been developed which predict driving impairment and fatigue to improve road safety and reduce accidents. However, these devices are not all readily available for average commuters who must rely on their own subjective assessments of driving ability. Subjective ratings have been linked with driving performance, but it is unclear how well self-rated ability predicts driving performance at different times of day – with and without sleep restriction. To address this, the aims of this study were to: (i) determine how sleep restriction and time-of-day affect simulated driving and self-rated ability; and (ii) to determine whether sleep restriction and time-of-day affect the predictive value of self-ratings.
Thirty-two male participants (M±SD; 22.8±2.9 years) lived in a time-isolation facility for 13 days. During this time, 16 participants completed a control condition, where they were provided an equivalent of 8h time in bed (TIB) per 24h, and 16 participants completed a sleep-restriction (SR) condition where they had an equivalent of 4h TIB per 24h. Throughout the protocol, sleep/wake opportunities were scheduled such that sleep and wake times were evenly distributed around the clock. During wake periods, self-ratings and driving performance were measured at 2.5-h intervals. Driving was assessed on a 10-min simulation task (DST), with the primary performance metric being lane deviation (standard deviation of lane position). Self-rated ability was measured on a 100-mm visual analogue scale (VAS) which asked participants rate “how well do you think you will perform?”
Mixed model analyses were conducted for lane deviation and self-rated ability to test for main effects and interactions. Significant main effects of condition and time-of-day were observed for both lane deviation and self-rated ability; scores were worse during the SR condition than the control condition and were worse at night than during the day. Time-of-day and condition interactions were observed such that ratings and performance during sleep restriction were even worse at night. Regression analyses were conduct with lane deviation as the dependent variable for both the control and SR conditions at each time of day. Lane deviation and self-rated ability were significantly correlated only for the SR condition, not the control condition. During SR, self-rated ability correlated with performance at most times of day except in the afternoon.
Understanding the factors that affect performance and the reliability of self-assessments can elucidate the circumstances where further precautions may be required. Lane deviation was more variable when sleep-restricted and at night. Self-ratings moderately predicted driving performance at most times of day during sleep restriction. These findings imply that people can self-monitor their ability to drive when fatigued. However, since the driving task was only 10-min, the results may not generalise to journeys longer than short commutes to/from work. Further research could investigate whether the ability to self-monitor driving performance changes over the course of a longer drive when fatigued.
Driving performance is worse when sleep restricted and worse at night. Self-ratings of ability can predict driving performance when fatigued at most times of day. As such, there is value in people self-report so appropriate responses can be made to mitigate risk.
Abstract:
Sophisticated technologies have been developed which predict driving impairment and fatigue to improve road safety and reduce accidents. However, these devices are not all readily available for average commuters who must rely on their own subjective assessments of driving ability. Subjective ratings have been linked with driving performance, but it is unclear how well self-rated ability predicts driving performance at different times of day – with and without sleep restriction. To address this, the aims of this study were to: (i) determine how sleep restriction and time-of-day affect simulated driving and self-rated ability; and (ii) to determine whether sleep restriction and time-of-day affect the predictive value of self-ratings.
Thirty-two male participants (M±SD; 22.8±2.9 years) lived in a time-isolation facility for 13 days. During this time, 16 participants completed a control condition, where they were provided an equivalent of 8h time in bed (TIB) per 24h, and 16 participants completed a sleep-restriction (SR) condition where they had an equivalent of 4h TIB per 24h. Throughout the protocol, sleep/wake opportunities were scheduled such that sleep and wake times were evenly distributed around the clock. During wake periods, self-ratings and driving performance were measured at 2.5-h intervals. Driving was assessed on a 10-min simulation task (DST), with the primary performance metric being lane deviation (standard deviation of lane position). Self-rated ability was measured on a 100-mm visual analogue scale (VAS) which asked participants rate “how well do you think you will perform?”
Mixed model analyses were conducted for lane deviation and self-rated ability to test for main effects and interactions. Significant main effects of condition and time-of-day were observed for both lane deviation and self-rated ability; scores were worse during the SR condition than the control condition and were worse at night than during the day. Time-of-day and condition interactions were observed such that ratings and performance during sleep restriction were even worse at night. Regression analyses were conduct with lane deviation as the dependent variable for both the control and SR conditions at each time of day. Lane deviation and self-rated ability were significantly correlated only for the SR condition, not the control condition. During SR, self-rated ability correlated with performance at most times of day except in the afternoon.
Understanding the factors that affect performance and the reliability of self-assessments can elucidate the circumstances where further precautions may be required. Lane deviation was more variable when sleep-restricted and at night. Self-ratings moderately predicted driving performance at most times of day during sleep restriction. These findings imply that people can self-monitor their ability to drive when fatigued. However, since the driving task was only 10-min, the results may not generalise to journeys longer than short commutes to/from work. Further research could investigate whether the ability to self-monitor driving performance changes over the course of a longer drive when fatigued.
Flexing the boundaries: Nurses' dynamic decision making for safety and care
Lookout!
Keywords: Risk perception, safety responsibility, railways
Author: Dr Anjum Naweed
Affiliation: Central Queensland University
Email address: anjum.naweed@cqu.edu.au
Lay summary:
On railways, track workers are protected by “Lookouts”, people who hold vigils for extended peroiods and send warnings to track workers when they see a train approaching. There are many vulnerabilities in this ways of working on a railway, and problems in the way that risk is perceived, that make it a flawed approach. We know this because track worker death in Australasia is ridiculously high. Ths presentation will disucss the make issues and present a compelling argument for a shift in the way track worker safety is managed.
Abstract:
Trains are the fastest and heaviest of land vehicles and the intent behind the design of railway sytems is to transport them safely and efficiently from one location to another. Track workers and track maintenance engineers are the usung heroes of rail safety but are often placed in hazardous situations, rendering them vulnerable to the very things they work to protect. This dramatic irony is reflected in the “Lookout Working” concept of safeworking, where a vigilant observer (called a Lookout) and a range of technologies are used to provide acceptable margins of personal safety from approaching trains.
A Lookout must detect the arrival of a train, effectively communicate the message of its approach to the track worker party, and occupy the ostensible role of a “human signpost” for the train driver. Yet, even if warnings are relayed, key vulnerabilities in the Lookout Working system mean that track workers are still at risk. No suitable safeplace may be provided for all track workers, or they may fail to move to a safeplace even though one is available. Track workers may also move out of a safe place into the path of an approaching train, or even move back on the track when there is a second train approaching.
This presentation will conceptualise the degrees of control and types of technologies used to protect the safety of track workers and maintain the security of their worksites. It will also describe the key non-technical dimensions that influence risk perception and culture of track working, such as levels of training and competency, procedures and language, and planning and productivity. Presented from a human factors approach of systems thinking, the presentation will articulate the main learnings that can be drawn from previous accidents and “near-hits” associated with failures in track worker protection, investigated in the context of Australasian and the UK rail.
Railways are underpinned by the ongoing tension between the need to improve capacity (run more trains and run them faster) and maintain the assets of the railway to support this capacity, such that the roles of the track worker and the corresponding Lookout have become culturally bound. The safest way for track workers to work on the railway would be to eliminate the hazard – the train – but this will not happen. Ultimately, the message is safety is your own responsibility. This presentation will explore Lookout Working as a flawed model of working in the current age, and ask the question, is it a necessary evil, or are we in dire need of a paradigm shift?
On railways, track workers are protected by “Lookouts”, people who hold vigils for extended peroiods and send warnings to track workers when they see a train approaching. There are many vulnerabilities in this ways of working on a railway, and problems in the way that risk is perceived, that make it a flawed approach. We know this because track worker death in Australasia is ridiculously high. Ths presentation will disucss the make issues and present a compelling argument for a shift in the way track worker safety is managed.
Abstract:
Trains are the fastest and heaviest of land vehicles and the intent behind the design of railway sytems is to transport them safely and efficiently from one location to another. Track workers and track maintenance engineers are the usung heroes of rail safety but are often placed in hazardous situations, rendering them vulnerable to the very things they work to protect. This dramatic irony is reflected in the “Lookout Working” concept of safeworking, where a vigilant observer (called a Lookout) and a range of technologies are used to provide acceptable margins of personal safety from approaching trains.
A Lookout must detect the arrival of a train, effectively communicate the message of its approach to the track worker party, and occupy the ostensible role of a “human signpost” for the train driver. Yet, even if warnings are relayed, key vulnerabilities in the Lookout Working system mean that track workers are still at risk. No suitable safeplace may be provided for all track workers, or they may fail to move to a safeplace even though one is available. Track workers may also move out of a safe place into the path of an approaching train, or even move back on the track when there is a second train approaching.
This presentation will conceptualise the degrees of control and types of technologies used to protect the safety of track workers and maintain the security of their worksites. It will also describe the key non-technical dimensions that influence risk perception and culture of track working, such as levels of training and competency, procedures and language, and planning and productivity. Presented from a human factors approach of systems thinking, the presentation will articulate the main learnings that can be drawn from previous accidents and “near-hits” associated with failures in track worker protection, investigated in the context of Australasian and the UK rail.
Railways are underpinned by the ongoing tension between the need to improve capacity (run more trains and run them faster) and maintain the assets of the railway to support this capacity, such that the roles of the track worker and the corresponding Lookout have become culturally bound. The safest way for track workers to work on the railway would be to eliminate the hazard – the train – but this will not happen. Ultimately, the message is safety is your own responsibility. This presentation will explore Lookout Working as a flawed model of working in the current age, and ask the question, is it a necessary evil, or are we in dire need of a paradigm shift?
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