Characterization of Sleep Quality and Heart Rate Variability in Emergency Medical Technicians: 2990 Board #305 May 29, 3

Emergency Medical Technicians (EMTs) must be alert and vigilant at all times to thwart potential errors in protocol and subsequent injury to citizens or each other. EMT work, which often includes 24-hour ‘on call’ shifts, overnight duty, rotating schedules, early awakening and interrupted nocturnal sleep, has been linked to increases in adverse health outcomes (e.g., sleep disorders and cardiovascular disease) as well as unintentional incidents such as motor vehicle collisions and occupational injuries. While peer-reviewed literature on EMT sleep quality is limited, even less is known about changes in cardiac autonomic tone during sleep as measured by heart rate variability (HRV). PURPOSE: To characterize sleep quality and HRV during sleep in a pilot sample of EMTs. METHODS: Within a larger study using remote data collection technologies, eight EMTs completed online sleep questionnaires, including five items from the Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS), on work days (WD) and non-work days (NWD). They also completed a daily sleep log capturing sleep onset and offset times, number of alarms and total time on shift on WDs. Sleep HRV was recorded using a physiological status monitor affixed to a chest strap during sleep. WD and NWD groups for all measures were compared using paired t-tests. RESULTS: EMT’s (age 27±7 years; BMI 25.9±3.0 kg•min2, mean±SD) reported sleeping significantly fewer hours per night following WDs (6.4±2) than following NWDs (7.7±1; P<0.05). HRV during sleep was significantly reduced after 24-hour ‘on call’ work shifts (SDNN=43.4±2.0 ms and HFn=24.3±1) when compared to regular work shifts (≤8 hrs) and NWDs (SDNN=61.1±1.0 ms and HFn=42.7±1; P<0.001). Scores on PSQI and ESS were worse on WDs compared to NWDs: 2.6±1 v 2.2±1 (P<0.05) and 8.0±4 v 7.4±4 (P<0.05), respectively. CONCLUSIONS: EMTs working 24-hour ‘on call’ shifts had shorter, fragmented sleep duration and decreased sleep efficiency resulting in greater cumulative exposure to increased sympathetic and decreased parasympathetic activity as measured via sleep HRV. These changes in cardiac autonomic tone may constitute one plausible pathway through which sleep deprivation may increase cardiovascular risk.