Rotational shift work is associated with sleep disturbances, increased risk of cardiovascular and psychological disorders, and may negatively impact work–life balance. The direction of shift rotation (Clockwise, CW or counterclockwise, CCW) and its role in these disorders are poorly understood. The aim of the study was to investigate the effect of the shift schedule direction on sleep quantity and quality, alertness and work performance, and on work–life balance on hospital nurses. One-hundred female nurses, working a continuous rapid shift schedule in hospitals in the north of Italy, participated in this cross-sectional study. Fifty worked on CW rotation schedule (Morning: 6 a.m.–2 p.m., Afternoon: 2 p.m.–10 p.m., Night: 10 p.m.–6 a.m., 2 rest days) and fifty on CCW rotation (Afternoon, Morning, Morning, Night, 3 rest days). Data were collected by ad hoc questionnaire and daily diary. During the shift cycle CW nurses slept longer (7.40 ± 2.24 h) than CCW (6.09 ± 1.73; p < 0.001). CW nurses reported less frequently than CCW awakening during sleep (40% vs. 80%; p < 0.001), attention disturbance during work (20% vs. 64%; p < 0.001), and interference with social and family life (60% vs. 96% and 20% vs. 70%, respectively; p < 0.001). CCW rotating shift schedule seems to be characterized by higher sleep disturbances and a worse work–life balance.

Orthostatic intolerance commonly occurs after prolonged bed rest, thus increasing the risk of syncope and falls. Baroreflex-mediated adjustments of heart rate and sympathetic vasomotor activity (muscle sympathetic nerve activity – MSNA) are crucial for orthostatic tolerance. We hypothesized that prolonged bed rest deconditioning alters overall baroreceptor functioning, thereby reducing orthostatic tolerance in healthy volunteers. As part of the European Space Agency Medium-term Bed Rest protocol, 10 volunteers were studied before and after 21 days of −6° head down bed rest (HDBR). In both conditions, subjects underwent ECG, beat-by-beat blood pressure, respiratory activity, and MSNA recordings while supine (REST) and during a 15-min 80° head-up tilt (TILT) followed by a 3-min −10 mmHg stepwise increase of lower body negative pressure to pre-syncope. Cardiac baroreflex sensitivity (cBRS) was obtained in the time (sequence method) and frequency domain (spectrum and cross-spectrum analyses of RR interval and systolic arterial pressure – SAP, variability). Baroreceptor modulation of sympathetic discharge activity to the vessels (sBRS) was estimated by the slope of the regression line between the percentage of MSNA burst occurrence and diastolic arterial pressure. Orthostatic tolerance significantly decreased after HDBR (12 ± 0.6 min) compared to before (21 ± 0.6 min). While supine, heart rate, SAP, and cBRS were unchanged before and after HDBR, sBRS gain was slightly depressed after than before HDBR (sBRS: −6.0 ± 1.1 versus −2.9 ± 1.5 burst% × mmHg −1 , respectively). During TILT, HR was higher after than before HDBR (116 ± 4 b/min versus 100 ± 4 b/min, respectively), SAP was unmodified in both conditions, and cBRS indexes were lower after HDBR ( α index: 3.4 ± 0.7 ms/mmHg; BRS SEQ 4.0 ± 1.0) than before ( α index: 6.4 ± 1.0 ms/mmHg; BRS SEQ 6.8 ± 1.2). sBRS gain was significantly more depressed after HDBR than before (sBRS: −2.3 ± 0.7 versus −4.4 ± 0.4 burst% × mmHg −1 , respectively). Our findings suggest that baroreflex-mediated adjustments in heart rate and MSNA are impaired after prolonged bed rest. The mechanism likely contributes to the decrease in orthostatic tolerance.

Objective: Indoor microclimate may affect students’ wellbeing, cardiac autonomic control and cognitive performance with potential impact on learning capabilities. To assess the effects of classroom temperature variations on the autonomic profile and students’ cognitive capabilities. Approach: Twenty students attending Humanitas University School, (14M, age 21  ±  3 years) underwent a single-lead ECG continuous recording by a portable device during a 2 h lecture when classroom temperature was set ‘neutral’ (20 °C–22 °C, Day 1) and when classroom temperature was set to 24 °C–26 °C (Day 2). ECGs were sent by telemetry to a server for off-line analysis. Spectral analysis of RR variability provided indices of cardiac sympathetic (LFnu), vagal (HF, HFnu) and cardiac sympatho-vagal modulation (LF/HF). Symbolic analysis of RR variability provided the percentage of sequences of three heart periods with no significant change in RR interval (0V%) and with two significant variations (2V%) reflecting cardiac sympathetic and vagal modulation, respectively. Students’ cognitive performance (memory, verbal comprehension and reasoning) was assessed at the end of each lecture using the Cambridge Brain Sciences cognitive evaluation tool. Main results: Classroom temperature and CO2 were assessed every 5 min. Classroom temperatures were 22.4 °C  ±  0.1 °C (Day 1) and 26.2 °C  ±  0.1 °C (Day 2). Student’s thermal comfort was lower during Day 2 compared to Day 1. HR, LF/HF and 0V% were greater during Day 2 (79.5  ±  12.1 bpm, 6.9  ±  7.1 and 32.8%  ±  10.3%) than during Day 1 (72.6  ±  10.8 bpm, 3.4  ±  3.7, 21.4%  ±  9.2%). Conversely, 2V% was lower during Day 2 (23.1%  ±  8.1%) than during Day 1 (32.3%  ±  11.4%). Short-term memory, verbal ability and the overall cognitive C-score scores were lower during Day 2 (10.3  ±  0.3; 8.1  ±  1.2 and 10.9  ±  2.0) compared to Day 1 (11.7  ±  2.1; 10.7  ±  1.7 and 12.6  ±  1.8). Significance: During Day 2, a shift of the cardiac autonomic control towards a sympathetic predominance was observed compared to Day 1, in the presence of greater thermal discomfort. Furthermore, during Day 2 reduced cognitive performances were found.

We hypothesized that sympathetic baroreflex mediated uncoupling between neural sympathetic discharge pattern and arterial pressure (AP) fluctuations at 0.1 Hz during baroreceptor unloading might promote orthostatic pre-syncope. Ten volunteers (32 ± 6 years) underwent electrocardiogram, beat-to-beat AP, respiratory activity and muscle sympathetic nerve activity (MSNA) recordings while supine (REST) and during 80° head-up tilt (HUT) followed by −10 mmHg stepwise increase of lower body negative pressure until pre-syncope. Cardiac and sympathetic baroreflex sensitivity were quantified. Spectrum analysis of systolic and diastolic AP (SAP and DAP) and calibrated MSNA (cMSNA) variability assessed the low frequency fluctuations (LF, ~0.1 Hz) of SAP, DAP and cMSNA variability. The squared coherence function (K2) quantified the coupling between cMSNA and DAP in the LF band. Analyses were performed while supine, during asymptomatic HUT (T1) and at pre-syncope onset (T2). During T2 we found that: (1) sympathetic baroreceptor modulation was virtually abolished compared to T1; (2) a progressive decrease in AP was accompanied by a persistent but chaotic sympathetic firing; (3) coupling between cMSNA and AP series at 0.1 Hz was reduced compared to T1. A negligible sympathetic baroreceptor modulation during pre-syncope might disrupt sympathetic discharge pattern impairing the capability of vessels to constrict and promote pre-syncope.