If you want to lose weight, but are not a fan of the gym, the results of a new study could offer a welcome alternative. People who wake up and go to bed at the same time every day are【C1】______than those with irregular sleep patterns, the study found. Researchers studied more than 300 women and found that those with the best—or most consistent—sleeping【C2】______had less body fat. The volunteers were【C3】______for body composition, and then were given an activity tracker to【C4】______their movements during the day, and their sleep patterns at night. The. study found that getting【C5】______than 6.5 hours, or more than 8.5 hours, sleep a night is【C6】______higher levels of body fat. Women with more than 90 minutes of variation in sleep and wake time during the week had higher body fat levels than those with less than 60 minutes of variation. Exercise science professor Bruce Bailey said【C7】______sleep quality can result in higher body fat【C8】______affecting the hormones levels【C9】______to appetite. He said: "We have these【C10】______clocks and throwing them off and not【C11】______them to get into a pattern does have a(an) 【C12】______on our physiology." He says there are ways to【C13】______sleep quality, such as【C14】______exercise, keeping your bedroom quiet and dark, and using beds only for sleeping. "Sleep is often a casualty of trying to do more and be better and it is often【C15】______," Professor Bailey said. Previous research from Temple University revealed that when people get a good night's sleep they don't feel so【C16】______They found that when children slept more, they【C17】______134 fewer calories a day and lost weight. These findings were supported by research from the Mayo Clinic in Rochester, Minnesota which also revealed that sleep【C18】______people eat more calories. The researchers studied 17 healthy young people and found that when they slept less they ate more. They believe this is【C19】______when the volunteers were tired, they had higher levels of the hormones leptin and ghrelin, both of which are【C20】______appetite.

【正确答案】 B

【答案解析】解析：由句首的They believe可知本句是就上句的研究发现when they slept less they ate more做出的解释。空格后when从句提到当这些志愿者疲倦时，他们体内的瘦素和胃饥饿素这两种荷尔蒙水平更高，上文已经提到荷尔蒙、睡眠和身体脂肪含量的关系，因此可推测这是他们吃更多东西的原因，故选B项because表示原因。