Exposure to more light during the day and less light at night is important for healthy sleep patterns because it helps to keep the right body clock, the study team writes in the journal Sleep Health. The results suggest that in office environment, being exposed either to daylight or electric lights that are rich in short wave blue light may be important for the health of workers. “Many office buildings may actually be moving in the direction of reducing light,” said Figueiro. “Much has been done to reduce light levels to promote energy efficiency, which is important, but we may be going too far in this direction.” she added, “We need to start thinking about how we light our daytime environment.” To see whether typical office workers get enough light to regulate their sleep-wake cycle, the study team found participants in five government office buildings across the United States. A total of 109 employees working at the offices wore light-measuring devices for one week in summertime, and 81 of these participants repeated the experiment in winter as well. The office workers wrote down their sleep and wake time and completed questionnaires about their mood and sleep quality at the end of each study period. Researchers found that people who were exposed to greater amounts of light during the morning hours, between 8 am and noon, fell asleep more quickly at night compared to those exposed to low light in the morning. People getting more morning light were also less likely to report feelings of depression and stress. Office workers who were exposed to high levels of light all day, from 8 am to 5 pm, also reported lower levels of sleep disturbance and depression. A lack of good quality sleep has been linked to mental and physical health problems, including issues with mood, thinking and the immune system. There are many easy things we can do during the day to increase our exposure to sunlight that could have beneficial effects on mood and sleep for many people, such as looking out of the window, seeking light during the day, especially during the morning, going out during lunch time.
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例句：They regulate the flow of water by the sluice gate.他们用水闸门控制水的流量。
efficiency /ɪ'fɪʃnsi/ n.效率;功率
例句：We must improve our efficiency as soon as possible.我们必须尽快地提高工作效率。！