Endocrine Abstracts

Objective: The present study was aimed to investigate the 24 h chronomics of BP/HR in terms of Double amplitude, Acrophase and Hyperbaric index and its relation with circadian rhythm of salivary cortisol in night shift nurses and actual day workers.

Material and methods: Fifty-six night shift nurses, aged 20–40 years, performing day and night shift duties were recruited from the Trauma Center, KGMU, India, and 56 age sex matched actual day workers were also enrolled as controls. BP and HR were recorded by ABPM at every 30 min intervals in day time and each hour in night time synchronically with circadian rhythm of salivary cortisol during shift duties.

Results: Highly significant difference was found in double amplitude (2DA) of SBP between night (23.10±14.68) and day shift (34.27±16.44) (P<0.0005). In night shift, hyperbaric index (HBI) of mean SBP was found to be increased at 00–03 am (midnight) while during day shift, peak was found at 06–09 AM. HBI of mean HR was found to be increased at 18–21 PM during night shift while in controls, peak was found at 09–12 & again 15–18 PM of SBP, DBP & HR. Alterations in Acrophase of BP/HR were very common among night shift workers and Ecphasia was found in few night shift workers. Significant difference was found in night cortisol levels among night (4.08±3.28) vs day shift (2.62±2.37), (P<0.005) while in comparison to night shift or day shift with controls these difference was highly significant (P<0.0005).

Conclusion: Reverse pattern of acrophase and HBI of BP & HR along with increases salivary cortisol level at night during night shift represents desynchronization. It indicates that the circadian rhythm was disrupted during night shift and it may be a risk factor for cardiovascular and other metabolic diseases in future after longer duration of rotating night shift.

Keywords: Circadian rhythm, Night shift, Ecphasia, Salivary cortisol and Desynchronization