sleep is a very important physiological activity we human beings carry out every day. averagely speaking, we spend at least 1/3 of our whole life time on sleeping.
a good night's sleep can make people feel refreshed and full of energy,while a minor deprivation of sleep might lead to fatigue, headache, languish and etc. it may cause temporary mental problems if one keeps awake consecutively for days. in a word, sleep is very important for us to funtion well in life and work. so we should have a healthy lifestyle and keep good habit of sleeping.