yes. It simulates the change in temperature in their natural environment during the winter months/ i.e. the breeding season. But there are many people who don't cool and have success as well so it really is a question of opinion. There are also people who have a level of control over their breeding facility's temperature where they can simulate a breeding season at any point in the year by using the cool down method. That's why you can see hatchlings entering the market in September, October, and sometimes as late as December.