Jillian Dorrian

Impact of Five Nights of Sleep Restriction on Glucose Metabolism, Leptin and Testosterone in Young Adult Men

Background Sleep restriction is associated with development of metabolic ill-health, and hormonal mechanisms may underlie these effects. The aim of this study was to determine the impact of short term sleep restriction on male health, particularly glucose metabolism, by examining adrenocorticotropic hormone (ACTH), cortisol, glucose, insulin, triglycerides, leptin, testosterone, and sex hormone binding globulin (SHBG). Methodology/Principal Findings N = 14 healthy men (aged 27.4±3.8, BMI 23.5±2.9) underwent a laboratory-based sleep restriction protocol consisting of 2 baseline nights of 10 h time in bed (TIB) (B1, B2; 22:00–08:00), followed by 5 nights of 4 h TIB (SR1–SR5; 04:00–08:00) and a recovery night of 10 h TIB (R1; 22:00–08:00). Subjects were allowed to move freely inside the laboratory; no strenuous activity was permitted during the study. Food intake was controlled, with subjects consuming an average 2000 kcal/day. Blood was sampled through an indwelling catheter on B1 and SR5, at 09:00 (fasting) and then every 2 hours from 10:00–20:00. On SR5 relative to B1, glucose (F 1,168 = 25.3, p<0.001) and insulin (F 1,168 = 12.2, p<0.001) were increased, triglycerides (F 1,168 = 7.5, p = 0.007) fell and there was no significant change in fasting homeostatic model assessment (HOMA) determined insulin resistance (F 1,168 = 1.3, p = 0.18). Also, cortisol (F 1,168 = 10.2, p = 0.002) and leptin (F 1,168 = 10.7, p = 0.001) increased, sex hormone binding globulin (F 1,167 = 12.1, p<0.001) fell and there were no significant changes in ACTH (F 1,168 = 0.3, p = 0.59) or total testosterone (F 1,168 = 2.8, p = 0.089). Conclusions/Significance Sleep restriction impaired glucose, but improved lipid metabolism. This was associated with an increase in afternoon cortisol, without significant changes in ACTH, suggesting enhanced adrenal reactivity. Increased cortisol and reduced sex hormone binding globulin (SHBG) are both consistent with development of insulin resistance, although hepatic insulin resistance calculated from fasting HOMA did not change significantly. Short term sleep curtailment leads to changes in glucose metabolism and adrenal reactivity, which when experienced repeatedly may increase the risk for type 2 diabetes.

The dynamics of neurobehavioural recovery following sleep loss.

Rate of recovery of daytime performance and sleepiness following moderate and severe sleep deprivation (SD) was examined when recovery opportunity was either augmented or restricted. Thirty healthy non‐smokers, aged 18–33 years, participated in one of three conditions: moderate SD with augmented (9‐h) recovery opportunities, moderate SD with restricted (6‐h) recovery opportunities, or severe SD with augmented recovery opportunities. Each participant attended the laboratory for 8–9 consecutive nights: an adaptation and baseline night (23:00–08:00 hours), one or two night(s) of wakefulness, and five consecutive recovery sleep opportunities (23:00–08:00 hours or 02:00–08:00 hours). On each experimental day, psychomotor vigilance performance (PVT) and subjective sleepiness (SSS) were assessed at two‐hourly intervals, and MSLTs were performed at 1000h. PSG data was collected for each sleep period. For all groups, PVT performance significantly deteriorated during the period of wakefulness, and sleepiness significantly increased. Significant differences were observed between the groups during the recovery phase. Following moderate SD, response speed, lapses and SSS returned to baseline after one 9‐h sleep opportunity, while sleep latencies required two 9‐h opportunities. When the recovery opportunity was restricted to six hours, neither PVT performance nor sleepiness recovered, but stabilised at below‐baseline levels. Following severe SD, sleepiness recovered after one (SSS) or two (physiological) 9‐h sleep opportunities, however PVT performance remained significantly below baseline for the entire recovery period. These results suggest that the mechanisms underlying the recovery process may be more complicated than previously thought, and that we may have underestimated the impact of sleep loss and/or the restorative value of subsequent sleep.

The sensitivity of a palm-based psychomotor vigilance task to severe sleep loss

In this study, we evaluated the sensitivity of a 5-min personal digital assistant—psychomotor vigilance test (PDA-PVT) to severe sleep loss. Twenty-one participants completed a 10-min PVT-192 and a 5-min PDA—PVT at two hourly intervals during 62 h of sustained wakefulness. For both tasks, response speed and number of lapses (RTs > 500) per minute significantly increased with increasing hours of wakefulness. Overall, standardized response speed scores on the 5-min PDA—PVT closely tracked those of the PVT-192; however, the PDA—PVT was generally associated with more lapses/minute. Closer inspection of the data indicated that when the level of sleep loss and fatigue became more severe (i.e., Day 3), the 5-min PDA—PVT was not quite as sensitive as the 10-min PVT-192 when 2- to 10-sec foreperiods were used for both. It is likely, however, that the observed differences between the two devices was due to differences in task length. Thus, the findings provide further evidence of the validity of the 5-min PDA—PVT as a substitute for the 10-min PVT-192, particularly in circumstances in which a shorter test is required and/or the PVT-192 is not as practical.

Train driving efficiency and safety: examining the cost of fatigue

This study investigated the effects of fatigue on train driving using data loggers on 50 locomotives operated by pairs of male train drivers (24–56 years) on an Adelaide–Melbourne corridor. Drivers’ work history was used to calculate a fatigue score using Fatigue Audit Interdyne Software. Trains were assigned to one of three groups, based on drivers’ maximum fatigue score: low (n = 15), moderate (n = 22) or high (n = 13) fatigue. Changes in driving parameters at different fatigue levels were investigated. A significant (P < 0.05) increase in fuel use was observed. Drivers in the moderate fatigue group used 4% more, and drivers in the high group used 9% more fuel than drivers in the low group. As these trains run daily, taking horsepower into account, this represents an approximate extra weekly cost of AUD

Introduction of an online approach to flexible learning for on-campus and distance education students: Lessons learned and ways forward

3512 using high compared with low fatigue drivers. High fatigue‐group drivers used less throttle and dynamic brake and engaged in more heavy brake and maximum speed violations. Comparison of three, 100 km track sub‐sections with undulating, flat, and hilly grade indicated that fuel use increases occurred primarily during the undulating sub‐section, and heavy brake and maximum speed violations occurred primarily in the flat sub‐section. Fatigued driving becomes less well‐planned, resulting in reduced efficiency (e.g. increased fuel consumption) and safety (e.g. braking and speeding violations). Fatigue may manifest differentially depending on track grade. In certain areas, fatigue will cause increased fuel use and economic cost, and in others, reduced safety through driving violations. These factors should be carefully examined in future railway operator research.

The effect of sleep restriction on snacking behaviour during a week of simulated shiftwork

While flexible delivery techniques, including online technologies, are becoming widely used to cater for the differing needs of students, they are not always met with enthusiasm, and can cause anxiety in students who are unfamiliar with the online environment. Online delivery of a first year nursing course (for distance learning and face-to-face provision) was introduced to facilitate reliable student-staff and student-student communication and streamline assessment procedures during a period in which class sizes increased (from 500 in 2003 to more than 650 in 2004 and 2005). Results of an evaluation exercise are presented, which aimed to: (1) trial online methods for course delivery and assignment submission; (2) canvass both student and staff responses to these innovations; (3) identify areas requiring change/improvement; and (4) formulate a strategy for improvement and continuing use of the technologies. Results suggested a positive response to the innovations by both staff and students. However, several implementation issues were identified, as were suggestions to overcome these initial hurdles. Iterative re-evaluation and continual development will examine the total benefit of these improvements. Taken together, this process has highlighted the importance of open communication, reducing anxiety and resistance to innovation, formal and informal evaluation processes and continued systems development.

Preparing our future counselling professionals: Gatekeeping and the implications for research

Due to irregular working hours shiftworkers experience circadian disruption and sleep restriction. There is some evidence to indicate that these factors adversely affect health through changes in snacking behaviour. The aim of this study was to investigate the impact of sleep restriction, prior wake and circadian phase on snacking behaviour during a week of simulated shiftwork. Twenty-four healthy males (age: 22.0 ± 3.6 years, mean ± SD) lived in a sleep laboratory for 12 consecutive days. Participants were assigned to one of two schedules: a moderate sleep restriction condition (n=10) equivalent to a 6-h sleep opportunity per 24h or a severe sleep restriction condition (n=14) equivalent to a 4-h sleep opportunity per 24h. In both conditions, sleep/wake episodes occurred 4h later each day to simulate a rotating shiftwork pattern. While living in the laboratory, participants were served three meals and were provided with either five (moderate sleep restriction condition) or six (severe sleep restriction condition) snack opportunities daily. Snack choice was recorded at each opportunity and assigned to a category (sweet, savoury or healthy) based on the content of the snack. Data were analysed using a Generalised Estimating Equations approach. Analyses show a significant effect of sleep restriction condition on overall and sweet snack consumption. The odds of consuming a snack were significantly greater in the severe sleep restriction condition (P<0.05) compared to the moderate sleep restriction condition. In particular, the odds of choosing a sweet snack were significantly increased in the severe sleep restriction condition (P<0.05). Shiftworkers who are severely sleep restricted may be at risk of obesity and related health disorders due to elevated snack consumption and unhealthy snack choice. To further understand the impact of sleep restriction on snacking behaviour, future studies should examine physiological, psychological and environmental motivators.

Performance on a simple response time task: Is sleep or work more important for miners?

Abstract Social science research specific to the identification and prevalence of unsuitable students within counselling, psychology, and social work training programmes is briefly reviewed in this article. This area of enquiry relates to the gatekeeping responsibilities of professional educational programmes, to ensure that their graduates are competent to provide ethical and effective practice to the public. Key issues which impede the usefulness of this gatekeeping literature to counselling educators are raised. These include: methodological inconsistencies which limit the comparison of findings and hence the drawing of sound conclusions; the lack of definitional clarity relating to the construct of gatekeeping; and the confusing array of nomenclature used to represent students’ failure to meet acceptable professional standards. It is apparent from this overview that there are common factors irrespective of nomenclature that are associated with students at risk of not becoming competent entry-level pra...

Sleep, stress and compensatory behaviors in Australian nurses and midwives

The purpose of the current study was to investigate the impact of work- and sleep-related factors on an objective measure of response time in a field setting. Thirty-five mining operators working 12-h shift patterns completed daily sleep and work diaries, wore activity monitors continuously and completed palm-based psychomotor vigilance tests (palmPVT) at the start and end of each shift. Linear mixed models were used to test the main effects on response time of roster, timing of test, sleep history and prior wake. The time at which the test occurred was a significant predictor of response time (F₃(,)₄₀₃(.)₄ = 6.72, p < .01) with the end of night shifts being associated with significantly slower response times than the start of night shifts, and the start or end of day shifts. Further, the amount of sleep obtained in the 24h prior to the test was also a significant predictor of response time (F₃(,)₄₀₇(.)₀ = 3.05, p < .01). The results suggest that, as expected, the end of night shift is associated with changes in response time indicative of performance impairments. Of more interest however is that immediate sleep history was also predictive of changes in response time with lower amounts of prior sleep related to slower response times. The current data provides further evidence that sleep is a primary mediator of performance, independent of roster pattern.

Changes in structural aspects of mood during 39—66 h of sleep loss using matched controls

OBJECTIVE To describe sleep, stress and compensatory behaviors in nurses and midwives. METHODS The study included 41 midwives and 21 nurses working in Australian hospitals between 2005 and 2009. Participation was voluntary. All participants recorded on a daily basis their work and sleep hours, levels of stress and exhaustion, caffeine intake and use of sleep aids for a month (1,736 days, 1,002 work shifts). RESULTS Participants reported moderate to high levels of stress and exhaustion on 20-40% of work days; experienced sleep disruption on more than 50% of work days; struggled to remain awake on 27% of work days; and suffered extreme drowsiness or experienced a near accident while travelling home on 9% of workdays. Age, perceived sleep duration and work hours were significant predictors of caffeine intake. About 60% of participants reported using sleep aids (about 20% reported taking prescription medications and 44% of nurses and 9% of midwives reported alcohol use as a sleep aid at least once during the study). Stress and workdays were significant predictors of sedative use. Overall, 22% reported being indifferent or mildly dissatisfied with their job. CONCLUSIONS Sleep problems, high levels of stress and exhaustion and low job satisfaction are prevalent among nurses and midwives. The use of alcohol and sleeping pills as sleep aids, and the use of caffeine to help maintain alertness is also common. Nurses and midwives may use caffeine to compensate for reduced sleep, especially on workdays, and sleeping pills to cope with their daily work-related stress.OBJETIVO: Descrever sono, estresse e comportamentos compensatorios em enfermeiras e parteiras. METODOS: O estudo incluiu 41 enfermeiras 21 parteiras em hospitais australianos de 2005 a 2009. A participacao foi voluntaria. Os participantes registraram diariamente as horas de trabalho, sono, stress e niveis de exaustao, cafeina e uso de ajuda para dormir durante um mes (1.736 dias, 1.002 turnos). RESULTADOS: Os participantes relataram de moderados a elevados niveis de stress e de exaustao em 20%-40% dos dias de trabalho; experimentaram disturbios do sono em mais de 50% dos dias de trabalho; relataram esforco para permanecer acordado em 27% dos dias de trabalho; e sofreram sonolencia extrema ou acidente perto de casa em 9% dos dias de trabalho. Idade, duracao do sono percebida e jornadas foram preditores significativos da ingestao de cafeina. Aproximadamente 60% dos participantes relataram utilizar a ajuda para dormir: cerca de 20% relataram uso de medicacao prescrita e 44% das enfermeiras e 9% das parteiras consumiam alcool como auxilio para dormir pelo menos uma vez durante o estudo. Estresse e dias de trabalho foram preditores significativos do uso de sedativos. Em geral, 22% relataram ser indiferente, ou ligeiramente insatisfeito com seu trabalho. CONCLUSOES: Problemas no sono, estresse e exaustao elevados e diminuicao na satisfacao no trabalho sao prevalentes. Sao comuns o uso de alcool e de medicamentos para dormir, e consumo de cafeina para se manter alerta. Enfermeiras e parteiras parecem usar a cafeina para compensar a reducao do sono, especialmente em dias de trabalho, e usar soniferos para compensar o estresse diario.