Biomedical subjects

Drew Dawson

Publications and source records attributed to Drew Dawson.

40 records · Page 3Linked to original sources

PubMed2002

Melatonin and zopiclone: the relationship between sleep propensity and body temperature.

STUDY OBJECTIVES: The sleep promoting effects of the sedative-hypnotics, melatonin and temazepam, have been associated with a decline in core body temperature (Tc). To determine whether changes in body temperature are a general feature of sedative-hypnotics, the present study compared the sleep inducing, core and peripheral temperature effects of melatonin, with those of zopiclone. DESIGN: Subjects were supine from 08:00-21:30 h and received melatonin, zopiclone or placebo at 14:00 h. SETTING: Individual, light and temperature controlled bedrooms. PARTICIPANTS: 12 healthy, young, adults (7m, 5f; 20.3 +/- 0.6 years). INTERVENTIONS: Melatonin (5mg), zopiclone (Imovane; 7.5 mg) and placebo were administered in a double-blind, crossover design. MEASUREMENTS AND RESULTS: From 11:00-20:00 h, modified hourly multiple sleep onset latency tests (MSLT) of a 20-min duration were conducted and heart rate (HR) was recorded. Tc and foot temperature (T(Ft)) were recorded continuously using thermistors. Compared with placebo, melatonin and zopiclone significantly reduced sleep onset latency (SOL) to stage 1 (by 3.50 +/- 0.73 min and 6.80 +/- 0.61 min, respectively) and reduced Tc (by 0.22 +/- 0.02C and 0.14 +/- 0.02C, respectively). For melatonin, Tc declined as the result of an increase in peripheral heat loss (increase in T(Ft) of 1.65 +/- 0.43 degrees C), and possibly a reduction in heat production as indicated by a decrease in HR (4.56 +/- 0.94 bpm). Zopiclone increased heat loss (increase in T(Ft) of 1.43 +/- 0.68C) and had no cardiac effects. For melatonin, a negative association was found between Tc (mean r=-0.43), however, this association was only weak for zopiclone (mean r=-0.23). CONCLUSIONS: These results suggest that body temperature changes may be a general feature of sedative-hypnotics. The potential role of this effect in the promotion of sleep appears to vary between agents.

Adult↗

PubMed2002

Effects of sleep pressure on endogenous cardiac autonomic activity and body temperature.

This study investigated the effects of variations in sleep pressure on cardiac autonomic activity and body temperature. In a counterbalanced design, 12 healthy, young subjects (6 men and 6 women) remained recumbent during 30 h of wakefulness (high sleep pressure) and 6 h of wakefulness (low sleep pressure). Both periods of wakefulness were immediately followed by a sleep opportunity, and the first 2 h of sleep were analyzed. During extended hours of wakefulness, a reduction in heart rate was mediated by a decline in cardiac sympathetic activity (measured via preejection period) and the maintenance of cardiac parasympathetic activity (measured via respiratory sinus arrhythmia). In subsequent high-pressure sleep, parasympathetic activity was amplified and sympathetic activity was negatively associated with electroencephalographic slow-wave activity. Sleep deprivation had no impact on foot temperature, but it did alter the pattern of change in core body temperature. A downregulation of cardiac autonomic activity during both extended hours of wakefulness and subsequent sleep may respectively provide "protection" and "recovery" from the temporal extension of cardiac demand.

Adult↗

PubMed2002

Circadian adaptation of aircrew to transmeridian flight.

BACKGROUND: Most research investigating the rate of circadian adaptation to transmeridian flight has focused on single, acute time zone transitions. Often however, aircrew experience compound time zone transitions, the physiological effects of which are not well understood. The primary aim of the current study was to investigate the circadian adaptation of a Royal Australian Air Force (RAAF) aircrew to several small time zone transitions using salivary melatonin onset as the marker of circadian phase. METHODS: Fifteen members of an RAAF aircrew collected saliva samples, sleep/wake records, and subjective alertness ratings during a 13-d surveillance patrol around the southwest Pacific Ocean. RESULTS: During the first 6 d of the surveillance patrol, the aircrew traveled 3.5 time zones east and melatonin onset advanced by 3.8 h. During the next 6 d the aircrew traveled 2 time zones west, but melatonin onset did not shift. Night-time sleep duration was shorter prior to workdays (6.4 h) than prior to rest days (8.4 h). Subjective alertness was not significantly affected by either the duration of night-time sleep prior to work, or the duration of flight. CONCLUSIONS: The melatonin onset results indicate that participants' body clocks adapted well to several small time zone transitions when initially traveling eastward, but did not adapt to a similar pattern of time zone transitions when subsequently traveling westward. This finding is contrary to expectations based on studies of single acute time zone transitions which indicate that adaptation to westward flight is more rapid than adaptation to eastward flight.

Adaptation, Physiological↗

PubMedDate not supplied

Compensation, benefits, and satisfaction: the Longitudinal Emergency Medical Technician Demographic Study (LEADS) Project.

OBJECTIVE: To determine the compensation, benefit package, and level of satisfaction with the benefits of nationally registered emergency medical technicians (NREMTs) in 2001. METHODS: The Longitudinal EMT Attribute Demographic Study (LEADS) Project included an 18-question snapshot survey on compensation with the 2001 core survey. This survey was sent to 4,835 randomly selected NREMTs. A total of 1,718 NREMT-Basics and NREMT-Paramedics, from 1,317 different postal zip codes, responded to the survey. RESULTS: Most NREMTs in the survey (86% of the compensated NREMT-Basics and 85% of the compensated NREMT-Paramedics) were employed primarily as patient care providers. For their emergency medical services (EMS) work in the previous 12 months, compensated NREMT-Basics had mean earnings of 18,324 US dollars (standard error, 978 US dollars) and compensated NREMT-Paramedics had mean earnings of 34,654 US dollars (standard error, 646 US dollars). At least 26% of compensated NREMT-Basics and 9% of compensated NREMT-Paramedics had no health insurance. The majority of compensated NREMTs (62% of the Basics and 57% of the Paramedics) reported their retirement plans were not adequate to meet their financial needs. EMTs are not satisfied with the appreciation and recognition they receive from EMS employers. About one-third (35% of the compensated NREMT-Basics and 30% of the compensated NREMT-Paramedics) were not satisfied with all of the benefits they receive from their EMS employer. Nearly all (94% of both compensated NREMT-Basics and NREMT-Paramedics) believed that EMTs should be paid more for the job that they do. CONCLUSIONS: The adequacy of EMT compensation and benefit packages is an area of concern. It is not unreasonable to believe that these factors are associated with EMT retention and attrition. Additional longitudinal EMT information on compensation and benefits are anticipated to determine the extent to which compensation and benefits are factors in EMT retention.

Adult↗