ABSTRACT
Objective To explore the sleep characteristics of submariners during a long-term voyage, so as to provide scientific evidence for ensuring submariners with good sleep during long-term voyages. Methods The sleep status of submariners who participated in a long-term voyage was tested by Self-Rating Scale of Sleep (SRSS) before the voyage, and before and after each voyage section during the voyage. The sleep status variation of submariners who performed different types of tasks, from the beginning to the end of each voyage section and of each resting-on-the-sea section was analyzed respectively. Comparison of sleep scores was performed between submariners and surface ship crew in the second voyage section. Numbers of submariners with sleep problem were compared in each voyage section. Results Generally speaking, submariners' sleep status at the end of voyage section was significantly worse than that at the beginning of voyage section and that before the whole voyage (P0.05). After finishing a voyage section and taking a resting-on-the-sea, submariners' sleep status returned to the level of pre-voyage (P>0.05), and was significantly better than that before the resting-on-the-sea (P0.05). Compared with that of surface ship crew who accomplished the same voyage section, submariners had an obviously better sleep status after taking a resting-on-the-sea (P0.05), but the latter was significantly more than the former when the second voyage section was finished (P<0.05). During the resting-on-the-sea period, the numbers of submariners with sleep problems in both the second and the third voyage section were significantly more than those in the first voyage section (P<0.05, P<0.01). The numbers of submariners with sleep problems who implemented the third voyage section were significantly more than those who implemented the first and the second voyage section (P<0.01). Conclusions Generally, the sleep quality of submariners is significantly worse after accomplished a voyage section task, and the degree of sleep problems may be accumulated to worse and worse along with the increase of long-term voyage time. Whereas, submariners may have a significantly better sleep status after taking a resting-on-the-sea, implying that resting-on-the-sea is an effective way to ensure submariners a good sleep during a long-term voyage.