题目内容：
根据下面资料，回答题 Energy Cycle
①Do you find getting up in the morning so difficult that it' s painful? This might be called laziness,but Dr. Kleitman has a new explanation. He has proved that everyone has a daily energy cycle.
②During the hours when you labor through your work you may say that you' re "hot".That' s true. The time of day when you feel most energetic is when your cycle of body temperature isat its peak. For some people the peak comes during the morning. For others it comes in the afternoonor evening.
③No one has discovered why this is so, but it leads to such familiar monologues ( 自言自语)as:" Get up ,John! You'll be late for work again!" The possible explanation to the trouble is thatJohn is at his temperature-and-energy peak in the evening. Much family quarrelling ends when husbands and wives realize what these energy cycles mean, and which cycle each member of thefamily has.
④You can' t change your energy cycle, but you can learn to make your life fit it better. Habitcan help, Dr. Kleitman believes. Maybe you' re sleepy in the evening but feel you must stay up lateanyway. Counteract (对抗) your cycle to some extent by habitually staying up later than you wantto. If our energy is low in the morning but you have an important job to do early in the day, rise before your usual hour. This won' t change your cycle, but you' 11 get up steam (鼓起干劲) and workbetter at your low point.
⑤Get off to a slow start which saves your energy. Get up with a leisurely yawn and stretch.Sit on the edge of the bed a minute before putting your feet on the floor. Avoid the troublesomesearch for clean clothes by laying them out the night before. Whenever possible, do routine work inthe afternoon and save tasks requiring more energy or concentration for your sharper hours.
Dr. Kleitman has proved that everyone has________.
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