It was the sock in the jaw that finally did it.
"We were lying in bed spooning when he had an elbow spasm and punched me in the jaw," says Barbara, a 55-year-old graphic designer from Lansing, Michigan, who asked that her last name not be used.
"I was already so sleep-deprived from his twitching and snoring that I was psychotic. After that, I just told him, 'It's all over, honey.'"
Barbara's husband of 22 years, who asked not to be identified, moved into another bedroom. They're among many loving couples who -- because of snoring, restless legs, opposite schedules or other nocturnal difficulties -- have decided to sleep apart.
A 2001 random telephone survey of 1,004 adults conducted by the National Sleep Foundation found that 12 percent of married Americans slept alone; a similar 2005 survey of 1,506 people found that number had jumped to 23 percent.
In addition, a March online survey of 1,408 couples conducted by the Sleep Council of England found that 1 in 4 people regularly retreats to a spare room or sofa to get a good night's sleep.
The preference for separate spaces has even begun to affect home design. According to the National Association of Home Builders, there's been a steady increase in the number of requests for "two-master bedroom" homes since 1990, prompting the organization to predict that by 2015, 60 percent of all custom upscale homes will be built with two "owner suites."