Centre for Sleep Research, University of South Australia, City East Campus, Frome Road, Adelaide, SA

The 7th Annual Meeting of the Australasian Chronobiology Society was held on Saturday 4th to Sunday 5th September 2010 at the Centre for Sleep Research in Adelaide.

CONFERENCE ABSTRACTS

The Keynote presentation was given by Professor Peter Clifton, CSIRO. Conference papers will be published by the Australasian Chronobiology Society (Edited by: Charli Sargent, David Darwent, Gregory D Roach; ISBN: 978-0-646-53863-1), and the individual papers are downloadable by clicking on the links below.

Download ACS Conference 2010 CHAPTER 1 The nature of the beast: Metropolitan train drivers experience, perception and recognition of fatigue (THOMPSON, RAINBIRD, DAWSON) Pages 1 - 5 Aims: Research on fatigue and train driving is characterised by the objective measurement and evaluation of workload and fatigue. Drivers' ability to individually recognise fatigue in situ is equally important. The aims of this paper are to outline the ways in which metropolitan rail drivers in an Australian capital city subjectively experience, perceive and recognise fatigue whilst they are driving. Methods: The present study employed a mixed-methods approach. It involved a closed-ended survey completed by 124 drivers that was contextualised through ethnographic focus groups and in-cab interviews involving a total of 48 train drivers. Results: Over three quarters of drivers reported experiencing 'zoning out' at the controls and one third or drivers reported having fallen asleep at the controls. Most drivers felt that fatigue was unavoidable. Drivers recognised fatigue through diminished reaction times and compromised situational awareness. Often, their recognition of fatigue was retrospective. Discussion: We discuss the need to develop drivers' prospective skills of fatigue recognition and pre-emptive action and suggest that this presents a target area for risk minimisation.

Download ACS Conference 2010 CHAPTER 2 Subjective mood is influenced by sleep-related and circadian processes in a forced desynchrony protocol with severe sleep restriction (HEATH, SARGENT, DARWENT, FERGUSON, KENNAWAY, HAMPTON, MATTHEWS, ROACH) Pages 7 -11 Aims: Studies show subjective mood declines when sleep is severely restricted to 4-5h per night. In addition, mood follows a circadian rhythm such that subjective mood is lowest around the circadian nadir. These findings are important for shiftworkers who often report severe sleep restriction and are subject to circadian disruption. The current study aims to examine the effect of prior wake and circadian phase on subjective mood when sleep is severely restricted to the equivalent of 4h of sleep opportunity per 24-h day. Methods: 14 healthy males (21.8 ± 3.8yr) lived in a time isolation laboratory for 12 consecutive days. Participants were scheduled to 3 x 24-h adaptation days (16-h wake episode, 8-h sleep opportunity), followed by 7 x 28-h forced desynchrony days (23.3-h wake episode, 4.7-h sleep opportunity). Total Mood Disturbance (TMD) was assessed every 2.5h during wake using the Profile Of Mood States scale. Core body temperature was continuously recorded with rectal thermistors and was used to determine circadian phase. Results: A significant effect of prior wake was found for TMD (p = <.001). Scores for TMD increased with duration of wakefulness. A significant effect of circadian phase was found for TMD (p = <.001). TMD scores were highest around the circadian nadir and lowest around the circadian acrophase. No interaction effects were found. Discussion: These findings suggest mood is influenced by sleep-related and circadian processes separately in a controlled laboratory environment when sleep is severely restricted. Field based research investigating sleeping patterns and mood in shiftworkers would provide further understanding of how other factors such as work and family mediate between sleep restriction/circadian disruption and mood in an external environment.

Download ACS Conference 2010 CHAPTER 3 The influence of circadian phase and prior wake on positive and negative mood during a sleep restricted forced desynchrony protocol (HAMPTON, DARWENT, MATTHEWS, HEATH, FERGUSON, SARGENT, KENNAWAY, ROACH) Pages 13 -17 Aims: To determine the effects of prior wake and circadian phase on subjective mood while employing a novel sleep restricted forced desynchrony (FD) protocol. It was hypothesised that positive mood (i.e. Vigour) would be influenced by a circadian and homeostatic process, whereas negative mood (i.e. Confusion, Tension, Anger, Depression, Fatigue) would not. Methods: 10 healthy males, with a mean (± SD) age of 22.3 (± 3.5) years and a body mass index of 22.8 (± 1.8) kg/m2 participated in a 28-h sleep restricted FD protocol. During the FD periods, participants were scheduled to 7h sleep and 21h wake (the equivalent of 6h sleep per solar day). Subjective mood was assessed using the Profile of Mood States (POMS) 1.5h after waking and every 2.5h thereafter. Circadian phase was assessed using the core body temperature rhythm that was sampled using a rectal thermistor (Steri-probe 491B). Results: Separate linear mixed-model ANOVA were conducted on the total mood disturbance score and individual mood subscales. The positive mood scale of the POMS (Vigour) showed main effects for circadian phase and prior wake. The negative mood scales of Fatigue, Confusion and Tension were also influenced by both processes. No significant effects of circadian phase or prior wake were found for Anger or Depression. Discussion: Very few studies have reported an influence of circadian phase or prior wake on negative mood states. No FD studies have yielded such results. Finding circadian and prior wake influences on 3 negative mood subscales within this FD study, could therefore be due to the use of the novel sleep restricted protocol, suggesting that negative mood is only influenced under reduced sleep. The findings from this study have practical implications as they give insight into how mood is affected when people receive 6h sleep per night which more closely mirrors that of today’s society.

Download ACS Conference 2010 CHAPTER 4 Sleep, wake and phase dependent changes in subjective alertness (ZHOU, FERGUSON, MATTHEWS, SARGENT, DARWENT, KENNAWAY, ROACH) Pages 19 - 23 Aims: To systematically examine the impact of prior wake, sleep dose and circadian phase on subjective alertness. Methods: Twenty-seven young males participated in one of two 12-day 28h forced desynchrony protocols varying in sleep dose (9.3h vs. 4.7h), where subjective alertness was assessed at various combinations of prior wake and circadian phase. Subjective alertness was measured using a visual analogue scale. Circadian phase was estimated using core body temperature. Results: A mixed-effects regression analysis with prior wake, circadian phase and sleep dose as fixed terms and participant as a random term revealed a sleep dose x prior wake x circadian phase interaction. Discussion: The sleep dose x prior wake x circadian phase interaction indicates that the adverse impact of sleep restriction on subjective alertness is prominent at early waking hours, particularly during the biological night.

Download ACS Conference 2010 CHAPTER 5 Does chronotype affect elite athletes capacity to cope with the training demands of triathlon? (LASTELLA, ROACH, HUREM, SARGENT) Pages 25 - 28 Aims: The aims of the present study were to identify the chronotype of Australia’s elite triathletes and to determine whether morning-types (M-types) compared to neither-types (N-types) and evening-types (E-types) are better able to cope with the demands of early morning training. Methods: Twenty-three elite triathletes (7 female and 16 male) from the Australian Institute of Sport were surveyed at the start of a training camp. Participants completed the Morningness-Eveningness Questionnaire (MEQ), Epworth Sleepiness Scale, and two questions concerning sleep satisfaction and sleep quality. Participants were assigned to a chronotype group on the basis of MEQ scores using the Horne and Ostberg classification system. Independent samples t-tests were used to compare subjective sleep variables (i.e. daytime sleepiness, sleep satisfaction, sleep quality) between chronotype groups. Results: Twelve participants were N-types, 11 were M-types and nil participants were E-types. There was no difference in daytime sleepiness, sleep satisfaction, sleep quality between M-types and N-types. There was no difference in the gender distribution between chronotype groups. Discussion: The results from the present study revealed that triathletes at the elite level tend to show either a morning or neither preference. There were no E-types within this sample of elite triathletes. This finding supports the notion that E-types do not select sports which require early morning training. Further, no differences were found for daytime sleepiness, sleep satisfaction, and sleep quality between Mtypes and N-types.

Download ACS Conference 2010 CHAPTER 6 The impact of organisational culture on fatigue management: The case of camaraderie amongst metropolitan train drivers (RAINBIRD, THOMPSON, DAWSON) Pages 29 -33 Aims: Metropolitan rail companies across Australia implement fatigue risk management strategies to ensure that train drivers are provided with adequate sleep opportunities. However, some risk management strategies, such as fatigue management training, are difficulty to operate in the workplace where drivers are influenced by organisational culture. This paper refers to metropolitan train drivers' intra-shift opportunities for rest and recovery and how implicit elements of the organisational culture, such as camaraderie, both aid and disrupt fatigue management. Methods: A qualitative fieldwork methodology was carried out over 2 weeks with participants from an Australian metropolitan rail company. The methodology included informal conversations, participant-observation, focus groups and one-to-one interviews with 48 train drivers. Results: Four opportunities for intra-shift rest and recovery were identified and included: standby, crib, and leaving a shift. Drivers reported being unable to make adequate use of these opportunities but felt compelled to complete their shift despite how tired they felt. Drivers reported assisting other drivers who were becoming increasingly fatigued by completing a run during their standby time. However, there was an unwillingness amongst drivers to be relieved mid-shift/run due to a concern that they will let their colleagues down. Drivers also referred to factors relating to an appropriate environment for rest and recovery that influenced their ability to adequately manage their fatigue. Discussion: There were explicit and also implicit elements of organisational culture. The implicit elements of organisational culture, particularly camaraderie, impacted on fatigue management both negatively and positively. Rail car drivers' response to fatigue was to continue their shift regardless of how tired they felt. Drivers identified some elements of current fatigue management training which are perceived as incompatible with the particularities of being a railcar driver. Future research will need to take into consideration organisational culture in identifying opportunities for more appropriate fatigue training and management.

Download ACS Conference 2010 CHAPTER 7 Young drivers knowledge of road safety, sleepiness and fatigue: Examining the internal consistency of the Institute for Breathing and Sleep Driver Awareness Questionnaire (IBAS-DAQ) (CORTES-SIMONET, KENNEDY, HOWARD, GILL, MCMAHON) Pages 35 - 39 Aims: To evaluate the psychometric qualities of the Institute of Breathing and Sleep Driver Awareness Questionnaire (IBAS-DAQ) and to determine whether gender differences existed in the scores within selected demographic variables and each subscale of the questionnaire. Methods: 176 participants (118 women, 67% and 58 men, 33%) aged between 18 and 26 (M = 21.2, SD ± 2.4) were recruited via convenience sampling from a university population and those of whom expressed an interest in participating completed the Institute for Breathing and Sleep Driver Awareness Questionnaire (IBAS-DAQ). Results: Reliability analysis and exploratory principal components factor analysis with a direct oblim rotation revealed that the overall structure of the modified IBASDAQ had strong internal consistency (α = 0.92). Each of the seven subscales within the IBAS-DAQ had a significant value of sampling adequacy, a linear relationship was observed among the variables and examination of the data indicated that each item was normally distributed. Gender differences within each subscale analysed via parametric two-tailed independent samples t-tests indicated that women had significantly higher scores in knowledge relating to fatigue symptoms and had significantly higher risky attitude scores than men. Men consumed more alcohol and had greater driving exposure. Discussion: The IBAS-DAQ was found to have strong internal consistency with the items within each subscale reflecting the different dimensions of the questionnaire including risky attitudes/behaviours and sleep/fatigue knowledge. Evaluating the relationship between these factors and crash risk attempting to modify these factors in young drivers has the potential to impact road crash risk in this population.

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