Circadian typology and sleep-wake patterns among air traffic controllers

Circadian typology and sleep-wake behavior

Natale, Martoni and Cicogna (2002¹) conducted research to describe the sleep–wake behavior of air traffic controllers with different circadian typology (morning and evening persons) and working a six-day cycle with backward rotation (13:00-20:00; 7:00-13:00, 20:00-7:00, and three rest days). This article provides a meta-analysis of the relevant results.

Illustration 1 shows differences between morning and evening types in three wake behaviors (activity, nap length and frequency of sleeping bouts). Evening-type air traffic controllers took more frequent and longer naps on day shifts, were moderately more active and took slightly longer naps on rest days, and were slightly more active after a night shift. In contrast, morning types took more frequent and longer naps after a night shift but did not show any discernible difference in main activity on day shifts.

Illustration 1: Wake differences between circadian types

Mean activity	d²	More active
On work days	0.02	—
On rest days	-0.59	evening
After night shift	-0.38	evening

Nap length	d²	Longer naps
On work days	-1.12	evening
On rest days	-0.35	evening
After night shift	0.78	morning

Sleeping bouts	d²	More bouts
On work days	-1.09	evening
On rest days	-0.11	—
After night shift	0.79	morning

Illustration 2 shows differences between morning and evening types in five sleep behaviors (restlessness, latency in falling sleep, awakening bouts, sleep quantity and sleep quality). Evening-type air traffic controllers had better sleep quality (efficiency) after a night shift and, moderately, on rest days, but also had slightly more awakenings from sleep on day shifts. In contrast, morning types slept longer during all three shifts but showed slightly better sleep quality during day shifts. They also showed longer delays in falling sleep, specially after a night shift, were moderately more restless after a night shift and on rest days, and had moderately more awakenings bouts, specially after night shifts.

Illustration 2: Sleep differences between circadian types

Mean activity	d²	More restless
Before morning shift	-0.11	—
On rest days	0.50	morning
After night shift	0.56	morning

Sleep latency	d²	Longer delay
Before morning shift	0.43	morning
On rest days	0.25	morning
After night shift	1.10	morning

Waking bouts	d²	More awakenings
Before morning shift	-0.17	evening
On rest days	0.18	morning
After night shift	0.48	morning

Sleep length	d²	Longer sleep
Before morning shift	1.26	morning
On rest days	0.73	morning
After night shift	0.70	morning

Sleep efficiency	d²	More efficient
Before morning shift	0.26	morning
On rest days	-0.37	evening
After night shift	-0.70	evening

Study's scope

The sample Air Traffic Controller group was carried out from a medium size airport which located in Italy. As a medium size airport, the traffic flow in the airport and the relative airspeace may vary from a big size international airport, in consequence, the ATC working pressure could be different when compare it with the ATC working in a high air traffic flow airport or airspace, the potential of different work load pressure and different work shift procedure than the subject in this research could influence the ATC's personal circadian rhythms and effect the sleep–wake behavior indirectly. Therefore, the limitation needs to be considered when study the consequences in lager airport or airspace.

References

1. NATALE Vincenzo, Monica MARTONI & Piercarla CICOGNA (2002). Effects of circadian typology on sleep–wake behavior of air traffic controllers. Psychiatry & Clinical Neurosciences (ISSN 1440-1819), 2003, volume 57, issue 5, pages 539-541. [DOI 10.1046/j.1440-1819.2003.01160.x]

+++ Notes +++

2. Effect sizes, d, calculated using the average standard deviation for each behavior. Conventional interpretation of Cohen's 'd': 0.2 = small difference, 0.5 = medium difference, 0.8 = large difference. The sign indicates whether the difference is in favor of the morning type [+] or the evening type [-].