Several factors can impact the rise of your cinnamon rolls including the age of your yeast, temperature, and humidity. Always check the expiration date of your yeast and make sure to activate it with liquid warmed to the temperature recommended by the yeast's manufacturer. Finally, if your kitchen is too cold it can cause your dough to rise more slowly. Overproofing can also cause cinnamon rolls to lose some of their fluffiness in the oven once baked.