Why do construction sites usually work at night, especially in the early morning?

According to the Law of People's Republic of China (PRC) on the Prevention and Control of Environmental Noise Pollution, construction is generally allowed from 6: 00 am to 22: 00 pm. Due to special needs (1, construction can't be carried out during the day due to bad weather; 2. Transport vehicles can't enter the construction site during the day; 3. Continuous operation must be carried out day and night due to special needs of the project; 4. Construction at night is really necessary for other special reasons), and construction can only be carried out after being reported to the environmental protection department for approval.