Chronic jetlag can cause cognitive deficits that can be permanent. This happens because the normal circadian rhythm of the body is disrupted. The endogenous system of circadian timing in the body adapts slowly. This disturbance can impair the physical and psychological health of the person.
When the circular muscles contract, the earthworm stretches, becoming longer and thinner. The earthworm uses its setae to anchor the front of its body in the soil. Now the longitudinal muscles contract and the earthworm becomes shorter and wider or it bends from one side to the other, pulling the body forward.
