Participants

The population studied was that of the submariners of the SSBN Le Triomphant, red crew, scheduled for a 60-80-day patrol in the autumn/winter of 2017-2018 (the dates of SSBN missions are classified as defense secrets). The inclusion criteria are as follows: existence of an informed and written consent from the patient; affiliation to a social security system; subjects judged fit for underwater navigation according to the regulations in force within the Army Health Service (Ministerial Instruction n°500 on medical aptitude for underwater navigation). 29 volunteer submariners, all male, were included. Their average age was 29.8 years (SD: 6.45). Of these, 23 were living with a partner (76.67%) and 14 had at least one child (48.27%).

The average length of service was 5,567 h on a nuclear attack submarine (NAS) (SD = 4,708) for the three submariners with NAS experience, and 6,835 h on an SSBN (SD = 6,505). The lowest work experience in the population was 0 h on NAS and 101 h on SSBN. The highest experience was 9,000 h on NAS and 25,000 h on SSBN. To illustrate what diving hours on an SSBN represent, an operational patrol corresponds to 2,000 h spent underwater. Three submariners from the population had never been on patrol on an SSBN before. For three other submariners, this was their last patrol.

In the population studied, eight submariners (27.6%) were on an “off-shift” schedule, working a day shift, with no night shift except for unforeseen interventions, and 20 (69%) were on a shift schedule (i.e., with a night shift every day) alternately between 8 P.M. and midnight, then between midnight and 4 A.M., and finally between 4 A.M. and 8 A.M. on the third night. One submariner did not specify his work rhythm.

Submariners reported an average weight before patrol of 75.96 kg [(60-97 kg); SD = 9.57]. Of 29 submariners, 24 (82.76%) were non-smokers. Two (6.89%) of the 29 submariners were left-handed.