"Evaluating sleep and sleep disorders from a dyadic perspective is important for several reasons. First, according to the 2005 National Sleep Foundation poll, 61% of adults sleep with a significant other, and one-quarter to one-third of married or cohabitating adults report that their intimate relationships are adversely affected by their own or their spouse's excessive sleepiness or sleep problems. Recent qualitative studies from interview data suggest that sleep problems in one or both partners, including insomnia symptoms and sleep-disordered breathing, contribute to marital problems. In addition, Ulfberg and colleagues found that women living with snorers were three times as likely to report symptoms of insomnia compared to women living with nonsnorers, suggesting that a sleep disorder in one spouse may increase risk for a sleep disorder in the other spouse, perhaps leading to additive or synergistic effects on the relationship quality."