Best way to cool down the house in the summer
The answer is yes if your area cools down significantly at night. The other factor to study is if your inside temperature stays lower than the outside temp, when all closed up, during the hottest part of the day. 

If cooler then closing up is the right strategy. If the inside approaches the outside temp then opening up and using fans to create air movement may be a reasonable strategy to pursue.  

Of course these comments apply when you have no auxiliary cooling going on during the hot days.