Shiftwork Adaptation: Morningness vs Eveningness

morningness eveningness

Does an individual’s circadian profile affect their ability to adapt to shiftwork?

Shiftwork Adaptation: Early Birds vs Night Owls

A person’s “circadian profile” tends to affect his or her ability to adapt to shiftwork. Three main characteristics of circadian profiles have been extensively evaluated: morningness/eveningness, flexibility of sleeping habits, and one’s ability to overcome drowsiness.

Morningness is associated with a reduced flexibility in sleep patterns—morning types find it more difficult to sleep during the morning hours than evening types, because of this rigidity in sleeping patterns, morning types’ struggle to adapt to night work.1

Shiftworkers in 24/7 operations who prefer to wake up late (after 9 a.m.), evening types, report sleeping more hours and getting better sleep when on the night shift schedule, as compared to morning types.

Researchers have found that after three years of shiftwork, one’s ability to overcome drowsiness is the best indicator of shiftwork tolerance. Both flexibility of sleep habits and ability to overcome drowsiness are associated with better long term shiftwork tolerance.1 Shiftwork intolerance, which occurs when workers never adjust to a shiftwork lifestyle, can result in health problems among workers and accompanying safety problems for an operation.

Consequences of Shiftwork Intolerance

Health Problems
Many shiftworkers suffer health problems due to the disruption of their circadian rhythms – especially when working rotating schedules.
Shiftwork intolerance can result in the following health problems: 2
  • Sleep disturbances and chronic tiredness
  • Gastrointestinal disturbances
  • Alcohol and drug abuse
  • Depression, fatigue, mood disturbances, malaise, personality changes
  • Interpersonal relationship difficulties
Safety Concerns
Shiftwork intolerance poses significant safety concerns to an operation as well.
Non-adapted workers report feeling drowsy and nodding off while working 3x more often than adapted workers, and also report making mistakes 4x more frequently than adapted workers (Figure 1).1
Figure 1. Alertness while working: well-adapted and non-adapted shiftworkers1

Shiftwork Lifestyle Training

Improved shiftwork adaptation seems to be associated with healthy behaviors during wakefulness that improve sleep quality (e.g. diet, exercise, scheduling).

Most shiftworkers are often times unaware of how to properly adjust their lifestyle to mitigate the negative effects of working around the clock. As a result, workers’ job performance, safety, health, and family life can suffer along with company profits and productivity levels.

Training workers on how to manage a shiftwork lifestyle is a powerful tool for improving your employees’ physical and psychological well-being, thereby increasing morale and adaptation to shiftwork.

In fact, research reports have found that turnover and absenteeism rates are lower in facilities that provide shiftwork lifestyle training.1

Download Our Free White Paper

Download our complementary CIRCADIAN® white paper, “Shiftwork Lifestyle Training: Employee and Employer Benefits
download now


CIRCADIAN® is the global leader in providing 24/7 workforce performance and safety solutions for businesses that operate around the clock. Through a unique combination of consulting expertise, research and technology, software tools and informative publications, CIRCADIAN helps organizations in the 24-hour economy optimize employee performance and reduce the inherent risks and costs of their extended hours operations.

1. CIRCADIAN. (2003). Health in Extended Hours Operations: Understanding the Challenges, Implementing the Solutions.
2. Costa, G. (1998). Guidelines for the medical surveillance of shift workers. Scandinavian Journal of Work, Environment and Health. 3; 151-155.
3. Scott, A., LaDou, J. (1990). Shiftwork: effects on sleep and health with recommendations for medical surveillance and screening. Occupational Medicine: State of the Art Reviews. 5(2); 273-299.

Additional Info

  • References:

Home  |  Privacy Policy  |  Terms of Use  |  Sitemap  |  Contact Us

Sign Up to Receive CIRCADIAN News.



Circadian Headquarters
2 Main Street, Suite 310
Stoneham, MA, 02180, USA

Contact Information
Local: 1.781.439.6300

©2020 Circadian ZircLight, Inc.
All rights reserved.