Acute mountain sickness can occur when a person ascends rapidly to 8000 feet (2400 meters). Symptoms of mountain sickness include headache, nausea, poor sleep, and general fatigue. An inexpensive drug (acetazolamide) taken the day before and during ascent reduces the symptoms of acute mountain sickness. Acute mountain sickness is more likely to occur after rapid ascent and poor acclimatization to high altitude. Obesity may promote acute mountain sickness. Its role is still unclear, largely because studies of the effects of obesity during rapid ascent are difficult to carry out during climbs in the mountains.