huge rise and fall of income

[TheMandarin]

ever since i turned on day/night cycle, i have experienced some huge rise and fall of income. before i turned on the cycle, my city generates on avg 11k to 12k per week. but after i turn on day night cycle, there are times when my city is only generating 40 bucks a week, and sometimes it goes as high as 20k per week. i have no idea what's causing that, is it because the citizens don't work when night time comes? thanks!

[Avanya]

Commercial and industry shuts down at night yes, so you don't gain any taxes from them while they're closed.