Jetlag is a temporary disorder caused by traveling across multiple time zones that results in the body's circadian rhythms being out of sync with the destination time. Symptoms include sleepiness, fatigue, headache, and memory loss. Both jetlag and shift work, where one works alternating day and night shifts, can disrupt biological rhythms and cause health issues like depression, sleepiness, and lack of mental alertness. To cure jetlag and shift work disorder, one should get deep sleep, do yoga, exercise, consume caffeine to stay alert during shifts, and make sure to entrain circadian rhythms through light exposure and a regular schedule.