Your’’re off work and hanging out at home. Off your diet and into cookies, big dinners and champagne. Off your schedule, and up nights with movies, videos or a good book. Off your workout routine and skipping your morning swim or evening run. In short, you’’re off, free of responsibilities and pressure, stuffed full of food and fun. And you don’’t like it. "All humans, and for that matter all species that are vertebrates and many that are not, have internal clock mechanism, "said George Brainard, professor of neurology at Thomas Jefferson University in Philadelphia." That’’s not a metaphor. It’’s an actual biological entity." As many people find themselves in the second week of enforced indolence because of the winter break -- whether because of school holidays or time off from work -- more than a few may be experiencing a peculiar sensation. A wave of discontent at the luxury of doing nothing, of sitting around with time to spare, the commodity of the late 20th century that we’’re constantly told is in dangerously short supply. The sense is that you should feel great, but actually you don’’t. You hate to admit it, but it might even be a welcome break to go back to work or school. "I enjoy being off, but I enjoy coming back too, "said Virgina Woodard of Chicago. After several days off around Christmas, she was back at her baby-sitting job on New Year’’s Eve, taking her 3-year-old charge to a museum. "It messes up your schedule, and coming back is tiresome," said Woodard, who nonetheless said she enjoyed her time off. "I feel like I’’ll need a week to recover to get back on my schedule, "said Joni Lederer. She and her family shared the holidays at their Highland Park home with another family, and she has spent the days since taking her two sons skating ,bowling and to museums. "Most people," said Brainard," do better and are healthier if they keep a regular social calendar to their life that is somewhat consistent with their internal timekeeping mechanism." The changes in routine that commonly occur during the holidays come at a biological cost. Those changes disrupt the body clock, located primarily in the brain, and may produce an out-of-sorts feeling. "Normal day-to-day routines and realities are very supportive of the internal clock structure that leads to good health," he added. When a person is off work and hanging out at home, he doesn’’t like it, why

A. He has nothing to do during the holidays and so he feels useless.
B. His routine timetable is changed so he doesn’’t feel comfortable.
C. He doesn’’t have any responsibilities and pressures, so he feels uneasy.
D. If he feels happy during the holidays, work will be more unbearable when the holidays are over.