The same group performed worse and had slower reaction times on the visual memory test. And their saliva samples showed higher levels of stress hormones. Mister Cho says he believes the brain needs at least ten days to recover after a long trip. He says airline workers told him their ability to remember got worse after working on planes for about four years. Other studies have shown that increased feelings of stress can cause a loss of cells in the part of the brain that controls memory.
Scientists say more tests are needed to study the effects of jet lag on the brain.
They want to find out if too much jet lag could permanently affect memory.