Avoid caffeine and nicotine. The stimulating effects of caffeine in coffee, colas, teas, and chocolate can take as long as 8 hours to wear off fully. Nicotine is also a stimulant.

• 睡前不要服用含咖啡因或尼古丁的物品。如咖啡、可乐、茶和巧克力中所含的咖啡因所长生的兴奋效应需要长达8小时才能完全消除。尼古丁同样是一个兴奋剂。