Which of the following is a common symptom experienced by divers under the influence of gas narcosis?

Gas narcosis, often referred to as nitrogen narcosis, occurs when divers descend to depths typically exceeding 30 meters (about 100 feet). As a diver goes deeper, the pressure increases, leading to a higher partial pressure of nitrogen in their lungs and, consequently, their bloodstream. This condition is known to affect the central nervous system and can cause various psychological and physiological symptoms.

Anxiety is a common symptom of gas narcosis because the diver experiences altered mental states or impaired judgment due to the effects of nitrogen on the brain. This can lead to feelings of unease or nervousness as a result of the impairment of cognitive processes. Divers may find themselves becoming overly cautious or unsettled, which can hinder their ability to respond adequately to the underwater environment.

The other options—excessive energy, increased cognitive function, and mental clarity—do not accurately represent the effects of gas narcosis. Instead, divers may experience decreased mental acuity and an overall sense of disorientation, which contrasts sharply with the notion of increased energy or cognitive abilities. Therefore, anxiety emerges as a symptom that divers should be aware of when they encounter the effects of narcosis during their deeper dives.