Spring sleepy, autumn fatigue, summer snooze. Once summer arrives, people are particularly prone to sleepiness, especially in the afternoon, can’t wait to minutes to “lie down”. As the weather gets hotter and hotter, many people yawn all day long: weakness, dizziness, anorexia …… no matter how long you sleep at night, once you get to daytime, you still have to resist the sleepiness. Strange, why are people so easily sleepy in summer? And how can we lift the old problem of summer sleepiness?