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Related Experiment Video

Updated: May 15, 2026

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments

Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments

Published on: August 8, 2019

QT and Tpeak-Tend intervals in shift workers.

Ioana Mozos¹, Liliana Filimon

¹Department of Functional Sciences, Victor Babes University of Medicine and Pharmacy, Timisoara, Romania. ioanamozos@yahoo.de

Journal of Electrocardiology

|January 15, 2013

Summary

Shift work prolongs cardiac QT and Tpeak-Tend (Tpe) intervals, particularly during night and morning shifts. Factors like hypertension, obesity, smoking, and longer shift work duration predict these cardiac changes.

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Area of Science:

Cardiology
Occupational Health
Electrocardiography

Background:

Shift work is prevalent globally, impacting circadian rhythms.
Alterations in cardiac repolarization, such as QT and Tpeak-Tend (Tpe) intervals, are critical cardiovascular parameters.
Understanding the cardiac effects of shift work is essential for occupational health.

Purpose of the Study:

To investigate the relationship between working time and cardiac repolarization intervals (QT and Tpe).
To identify factors associated with the prolongation of QT and Tpe intervals in shift workers.

Main Methods:

A total of 60 shift workers were enrolled.
Standard 12-lead electrocardiograms (ECGs) were recorded during morning, afternoon, and night shifts.
QT intervals and T wave variables (including Tpe) were manually measured.

Main Results:

QT and Tpe intervals were significantly prolonged during night and morning shifts compared to afternoon shifts.
Increased QT and Tpe interval durations were associated with hypertension, older age, smoking, higher body mass index, and longer duration of shift work.
Cox regression identified independent predictors for prolonged QT (age, hypertension, BMI) and Tpe intervals (age, smoking status).

Conclusions:

Shift work, especially night and morning shifts, leads to cardiac repolarization prolongation (QT and Tpe intervals).
Hypertension, overweight/obesity, smoking, and prolonged shift work exposure exacerbate this prolongation.
Age, hypertension, and BMI are independent predictors of QT prolongation, while age and smoking predict Tpe prolongation, highlighting risks for specific worker groups.