6-26 U.S. Navy Diving Manual — Volume 2 Navy divers are less aware of the effects of fatigue on their performance. The causes of fatigue include long hours of work as well as a lack of sleep. Factors such as stress, temperature extremes, noise (>80 dB), hyperbaric pressure, and physical work vibration also induce fatigue. Thus, a combination of cold or hot water, greater depth, and long work hours combine to create a fatigue-inducing environment. The effects of fatigue can be compared to the effects of alcohol consumption. Even a loss of two hours sleep produces a performance decrement equivalent to two or three alcoholic beverages. Effects of fatigue may include: 1. Degradation in ability to think: n Inflexible decision making and loss of innovative thinking. n Reduced ability to cope with unforeseen rapid changes. n Inability to adjust plans when new information becomes available. n Tendency to adopt more ridgid thinking. 2. Reduced coordination in motor skills and timing. 3. Inhibited ability to communicate. 4. Social degradations: n Irritable or withdrawn. n Less tolerant of others and more acceptance of own errors. n Neglect of smaller tasks (inattention to detail). n Increasingly distracted by discomfort. 5. Increase in risk of decompression sickness. The Dive Supervisor must maintain an awareness of the effects of fatigue on the dive team and mitigate the condition to avoid mishaps. All team members should have a minimum of four to five hours of continuous sleep prior to diving. Divers performing particularly hazardous dives, or dives that expose them to higher risk of DCS, should obtain more sleep if possible. Rotating dive station positions, obtaining short 10-minute intervals of sleep, and performing short bouts of exercise may improve functioning if obtaining adequate sleep is not possible. The Dive Supervisor may need to halt diving operations during sustained missions to rest, recuperate, and restore individual and team functioning. 6-6.3.4 Stress. A certain amount of stress is normal and even beneficial to motivation and performance. The Dive Supervisor’s concern is when stress adversely affects performance that may lead to mishaps.

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