The Effects of Individual Characteristics of the Naval Personnel on Sleepiness and Stress during Two Different Watchkeeping Schedules

Mikko Myllylä (), Heikki Kyröläinen, Tommi Ojanen, Juha-Petri Ruohola, Olli J. Heinonen, Petteri Simola, Tero Vahlberg and Kai I. Parkkola
Additional contact information
Mikko Myllylä: Centre for Military Medicine, The Finnish Defence Forces, 20241 Turku, Finland
Heikki Kyröläinen: Neuromuscular Research Center, Faculty of Sport and Health Sciences, University of Jyväskylä, 40014 Jyväskylä, Finland
Tommi Ojanen: Human Performance Division, Finnish Defence Research Agency, The Finnish Defence Forces, 04310 Tuusula, Finland
Juha-Petri Ruohola: The Navy Command Finland, The Finnish Defence Forces, 20811 Turku, Finland
Olli J. Heinonen: Paavo Nurmi Centre & Unit of Health and Physical Activity, University of Turku, 20520 Turku, Finland
Petteri Simola: Human Performance Division, Finnish Defence Research Agency, The Finnish Defence Forces, 04310 Tuusula, Finland
Tero Vahlberg: Department of Biostatistics, University of Turku, 20014 Turku, Finland
Kai I. Parkkola: Department of Leadership and Military Pedagogy, National Defence University, 00861 Helsinki, Finland

IJERPH, 2022, vol. 19, issue 20, 1-17

Abstract: Background: Naval service can have a significant impact on the wellbeing of seafarers, and the operation of warships is highly dependent on the personnel on board. Nevertheless, there is a lack of knowledge concerning the impact of seafarers’ individual characteristics on their wellbeing in a naval environment. Therefore, the aim of this study was to investigate individual characteristics of the naval personnel that may be associated with the amount of sleepiness, fatigue and stress responses experienced during shift work and irregular working hours in a naval environment. Methods: The study took place on a Finnish Defence Forces’ Navy missile patrol boat on which 18 crewmembers served as study participants. The measurement periods lasted two separate weeks (seven days and six nights) during shift work with two different watchkeeping systems (4:4, 4:4/6:6). The onboard measurements consisted of the Karolinska Sleepiness Scale, salivary stress hormones, cognitive tests (Sustained Attention to Response Task and N-back Task) and heart rate variability. Results: Participants of older ages or with a longer history in naval service were associated with a greater amount of sleepiness, fatigue and stress responses on board. On the contrary, increased physical activity and a higher level of physical fitness, especially standing long jump, were associated with a lower amount of sleepiness, fatigue and fewer stress responses. In addition, an athletic body composition together with a healthy lifestyle may be beneficial, considering the stress responses on board. Conclusion: The present results are well in line with the previous literature regarding shift work and irregular working hours. The results highlight the importance of regular physical activity and good physical fitness during service in the naval environment.

Keywords: individual characteristics; individual factors; shift work; watchkeeping; irregular working hours; sleepiness; fatigue; stress; navy (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2022
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