Airsickness
Airsickness is produced by a disturbance of the labyrinthine of the inner ear, although psychogenic such as apprehension can also play a part. Motion sickness can be prevented by taking drugs containing scopolamine or some antihistamines before flying.

Time Change
As planes became faster, pilots and passengers were able to travel across many time zones in less than a day. The resulting disturbance in the body's "biological clock" or circadian ("about a day") rhythm can produce disorientation and reduce and efficiency. This condition is popularly known as jet lag. While troublesome to passengers, the problem is more acute for pilots, who may have to fly another in a short time. Concern has been expressed about the possible effect of this situation on air safety, although no air accident has yet been clearly as jet-lag-.

Space Medicine
Specialists in space medicine - a discipline also known as bioastronautics - study the human in flight outside the atmosphere. Most of the dangers in space travel (such as acceleration and deceleration forces, the need for an artificial atmosphere, and noise and vibration) are to those in atmospheric flight, and can be for in ways. Space-medicine scientists, however, must consider two additional problems-weightlessness and the increased radiation outside the atmosphere.

History
The first information about human performance during space travel was gathered in Germany in the 1940s under the direction of Hubertus Strughold. Both the United States and the former Union of Soviet Socialist Republics (USSR) rocket tests with animals from 1948. In 1957 the USSR put a dog into the earth's orbit, and the United States used a monkey for tests in 1958. The tests suggested that few biological dangers existed in space flight. This was when human space flight began on April 12, 1961, with the launching of the Soviet cosmonaut Yury Gagarin into orbit.

The United States followed with the Mercury-Redstone suborbital flights, and then the orbital Mercury and Gemini flights, the Apollo moon landings, the experimental orbital Skylab, and Space Shuttle flights. Then, in the 1980s, when Soviet cosmonauts began setting records for time spent in the gravity-free or "microgravity" , the effects of long-term weightlessness began to be viewed as a serious problem.