Although it might be the way its written, but Dubois leaving the cockpit seems to come at the worst possible time too, right before they're about to hit a storm

Although it might be the way its written, but Dubois leaving the cockpit seems to come at the worst possible time too, right before they're about to hit a storm and the junior officer is nervous. Although he may have known he really needed the sleep, which is also a problem due to lack of sleep.