Many heterosexual couples discover an uncomfortable truth: women often sleep worse when sharing a bed with their male partner. While this isn’t universal, research shows consistent patterns explaining why co-sleeping affects women more. This heightened sensitivity comes from evolutionary wiring: historically, women were more likely to wake to protect infants or respond to threats. Even today, a shifting or snoring partner can easily disrupt their sleep.
These hormonal patterns can magnify sleep disruptions caused by a partner. Men tend to sleep more deeply beside a partner than women do. Better sleep often leads to a better relationship — whatever arrangement makes that possible. For a lighter sleeper, even small movements can trigger a partial wake-up. Over the course of the night, this leads to poorer sleep consolidation for women. This mental pressure creates a feedback loop: worry → wakefulness → more worry.
