Space sickness is a condition experienced by about half of all astronauts when adapting to weightlessness. According to the symptoms, the condition is similar to seasickness: decreased appetite, dizziness, headache, increased salivation, nausea, vomiting sometimes occurs, spatial illusions. All these effects usually go away on the first day.
The astronaut’s unhealthy state arises due to the adaptation of the vestibular apparatus to weightlessness, a violation of the interaction of other sensory systems of the body and the redistribution of blood in the body.
Unpleasant sensations and symptoms associated with space adaptation syndrome vary in severity. About 50% of astronauts experience moderate discomfort (nausea, headache, disorientation); approximately 10% have a severe reaction (vomiting, other symptoms that completely deprive a person of the opportunity to work normally during the habituation period).