Physiological recovery from night-call duty – a field study of physicians

Purpose Adverse eVects by night-call duty have becomean important occupational health issue. The aim of thisstudy was to investigate whether the heart rate variability(HRV) diVered during recovery from day work and night-call duty between distinct physician specialities.Methods We studied the impact of a 16-h night-call dutyon autonomic balance, measured by HRV, among two phy-sician groups diVering with respect to having to deal withlife-threatening conditions while on call. Nineteen anaes-thesiologists (ANEST) and 16 paediatricians and ear, noseand throat surgeons (PENT) were monitored by ambulatorydigital Holter electrocardiogram (ECG). Heart rate variabil-ity was analysed between 21:00 and 22:00 after an ordinaryworkday, on night call and in the evening post-call. Abso-lute and normalized high-frequency power (HF, HFnu)were the main outcome variables, expressing parasympa-thetic inXuence on the heart.Results ANEST had lower HF power than PENT whileon night call and post-daytime work (p < 0.05), but not atpost-night call. In the whole group of physicians, HFnu waslower on call and post-daytime work compared with post-night-call duty (p < 0.05).Conclusions The physiological recovery after night dutyseemed suYcient in terms of HRV patterns for HFnu,reXecting autonomic balance and did not diVer betweenspecialities. However, the less dynamic HRV after daytimework and during night-call duty in the ANEST group mayindicate a higher physiological stress level. These resultsmay contribute to the improvement of night-call scheduleswithin the health care sector.