Answer:
The activity of the yeast drops with the cooler night-time temperatures
Step-by-step explanation:
The temperature in your house is probably warmer in the day than at night.
The yeast acts on carbohydrates in the dough to form carbon dioxide gas, which causes the dough to rise.
However, the yeast has its maximum activity at about 27 °C. If the temperature drops to 21 °C, the rise time will double. If the temperature rises to 35 °C, you have effectively killed the yeast, and the bread will not rise.
A reasonable temperature to aim for is 21 °C to 27 °C.