Greyout
With greyout is in aviation medicine , the precursor of the blackout called. This occurs with pilots in aviation and with people who take part in acceleration tests in centrifuges.
During the action of the acceleration on the body, the brain is no longer adequately supplied with oxygen due to the sagging of the blood , and the field of vision is narrowed ( tunnel vision ) and color vision is clouded. However, awareness and the ability to act are not yet affected. If the acceleration continues, the blackout is followed by a sudden, short-term unconsciousness. With the correct use of press breathing , trained pilots can delay the grayout or blackout. The greyout starts at around 4 to 6 g , depending on the physical condition of the pilot. After the acceleration is stopped, the body recovers within a few seconds.