Sleep and wake are shared and transmitted between individuals with insomnia and their bed-sharing partners.

Patients with insomnia frequently report disturbing, or being disturbed by, their bedpartner. We aimed to (1) characterize how individuals with insomnia and their bedpartners influence each other's sleep and (2) identify characteristics predicting vulnerability to wake transmission. Fifty-two couples (aged 19-82 years), where one individual was diagnosed with insomnia, participated. Sleep/wake patterns were monitored via actigraphy and sleep diaries for seven nights. Minute-by-minute sleep and wake concordance (simultaneous sleep/wake epochs), number of wake transmissions received (awakenings immediately preceded by wakefulness in the bedpartner), percent wake transmissions received (percentage of total awakenings that were transmitted), and percent of bedpartner's wake minutes resistant to transmission (ability to sleep through bedpartner wakefulness) were calculated. Mixed-effects modeling assessed within-couple bedtime and chronotype differences as predictors of dyadic sleep. We described rates of sleep concordance (MPatient = 63.8%, MPartner = 65.6%), wake concordance (MPatient = 6.6%, MPartner = 6.6%), total transmissions received (MPatient = 5.5, MPartner = 6.9 per night), percent transmissions received (MPatient = 18.5%, MPartner = 23.4% of total awakenings), and percent minutes resistant (MPatient = 56.4%, MPartner = 58.6% of bedpartner's wake time). Partners received wake transmissions at 1.25 times the rate of patients. Percent transmissions received was increased in couples with concordant bedtimes and individuals with later chronotype than their bedpartner. Patterns of chronotype and bedtime order predicting percent minutes resistant to transmission differed across the length of the rest interval. Transmission provides a novel characterization of how bedpartners influence sleep and provide insight into mechanisms of insomnia generation and maintenance. Understanding modifiable risk factors may provide ways to personalize insomnia treatments. Clinical Trial Researching Effective Sleep Treatments (Project REST), ANZCTR Registration: ACTRN12616000586415.