A non-saturated mixed-gas dive to 180 meters depth was carried out at JAMSTEC, using diving simulator (hyperbaric chamber) facilities. Compression started at 10:00h with helium and oxygen and was carried out at a rate of 12m/min. Decompression started at 11:15h using the Comex Helox 180 Diving Manual. Decompression to 1 ATA required 49.2h.
A survey of subjective symptoms, sleep feelings and ball-bearing tests were performed. All night electrophysiological recording of subjects' sleep was performed and polygraphic analysis of nocturnal sleep was done with visual scoring.
The results were as follows:
Arriving at 180 meters, the complaint rate was 39.2% and fatigue was greater. The type of fatigue that was based on the composion ratio of symptoms was that of mental fatigue. During the decompression it was recovery.
The performance in the ball-bearing test decreased about 20% at a depth of 180 meters because of tremors and disturbance of attention as well as other factors showing symptoms of high-pressure nervous syndrome.
The sleep feelings were different in experimenced persons and nonexperimenced persons. The non-experienced persons had markedly decreased REM stages and slept badly all night.
Based on these results, fatigue and the performance of divers were discussed.
