Health Benefits of a God Night's Sleep
Sleep, we all love it, especially when we wake up from a great night's sleep. _____（26）But nowadays we are beginning to understand the importance of sleep to overall health.
People working the night shift have a higher risk of cancer. Researchers believe this link is caused by differing levels of melatonin（褪黑素）in people who are exposed to light at night. _____（27）Melatonin makes us sleepy and is thought to protect against cancer. Be sure that your bedroom is dark to help your body produce the melatonin it needs.
When your body is short of sleep, it goes into a state of stress. The body's functions give you an alarm which causes an increase in blood pressure. _____（28）Learn to relax to reduce the effects of stress.
Researchers have also fund that people who sleep less than seven hours per night are more likely to be fat. _____（29）So if you are interested in controlling or losing weight, don't forget to pay attention to getting a good night's sleep.
Sleeping during the day will protect your health and make you more productive. A study of Greek adults showed that people who slept during the day several times a week had a lower risk of dying from heart disease. _____（30）
（28）_____
A、Higher blood pressure increases your risk for heart attacks.
B、It is thought that the lack of sleep affects appetite.
C、In the past, sleep was often ignored by doctors and surrounded by myths.
D、Exposure to light during early waking hours helps to set your body clock.
E、Short-time sleep also improves memory, learning ability and mood.
F、Light exposure reduces the level of melatonin.
【正确答案】：A
【题目解析】：空前讲的是缺乏睡眠会导致人们处于应激状态，导致血压升高。A项讲的是血压升高会导致心脏病发作几率上升，与空前衔接紧密，故选A。
