Raj Dasgupta, MD, says, the conditions under which couples have sex often have as much to do with whether men or women get sleepy after sex as do their postcoital hormonal differences, reports Fox News.

Dasgupta explained that most couples have sex at night, potentially in cool, quiet rooms, likely in a comfortable bed — in other words, the perfect environment for sleeping. And for those men who may have sleep apnea, the aforementioned conditions can create the perfect environment for dozing off.