Not only is sleep linked with lower stress， better productivity， and a stronger immune system， but studies link good sleep with a healthier weight． The only question is， how many hours should you clock in to gain those benefits？
To find out how sleep time affects diet during the day， researchers gathered 42 adults who admitted they don't sleep much every night． Half of the participants kept their normal sleep schedule， while half were trained in the sleep pattern with the goal of helping them sleep an extra 90 minutes every night． All the volunteers wore wrist monitors to track their sleep time．
After four weeks， the trained group in good sleep habits added an average of 47 minutes between the time they fell asleep and woke up compared to the group that didn't change its schedule， according to the results in the American Journal of Clinical Nutrition． Plus， 86 percent of the trained group started spending more time in bed， adding an extra 55 minutes instead of 47 minutes on average．
That extra sleep showed some real-world benefits that could help explain why lack of sleep is associated with fatness． The sleep-trained group ate an average of 176 fewer calories（卡路里） a day； in comparison， the other group ate only seven fewer calories every day． Best of all， those calories were cut from less healthy sources． Those who slept more cut ten grams of sugar from their diets every day， while the others changed their sugar intake by less than a gram．The newly better sleepers also ate their daily carbs（碳水化合物）reduced by 22 grams， while the shorter sleepers actually ate 3 more grams．Even with better sleep and dietary habits， the participants didn't show much weight change over the course of the study， but the results are consistent with past research linking sleep with a healthy weight， like one study that found people burn more fat when getting a full night's rest．
The researchers are optimistic that a little extra shut-eye could be the help people need when trying to lose pounds．"Our results …suggest that increasing time in bed for an hour or so longer may lead to healthier food choices，" Haya Al Khatib， PhD， tells King's College London．



How many extra minutes did the trained group sleep at least？ ______

A. 47
B. 55
C. 86
D. 90

According to Paragragh 4， a shorter sleeper is likely to ______ ．

A. consume less sugar
B. burn more fat
C. eat more calories
D. eat fewer carbs

Which of the following statements is true according to the passage？ ______

A. Healthy sleep and habits leads to apparent weight change．
B. Half of the participants were asked to wear wrist monitors in the study．
C. The sleep-trained group choose more unhealthy sources a day than the other group．
D. The two groups both reduced their sugar intake by diverse amounts．

What can we conclude according to the passage？ ______

A. More sleep， less weight．
B. Go to bed the moment it is possible．
C. Additional appropriate sleep can help keep fit．
D. Increasing time in bed contributes to healthier food choices．