We hypothesized that infant sleep disorders would be significantly associated with infant-mother attachment status. Using current attachment theory, we specifically predicted that infants classified as insecure-avoidant would contrast with those classified as insecure-resistant (at 15 months of age) in terms of incidence and length of night wakings (at ages 6 and 15 months), as well as clinical sleep problems. Analyses of sleep and attachment data gathered on the insecure subset (n=342) of a larger sample of more than 1,000 mother-infant pairs indicated, as predicted, that infants with insecure-resistant attachments (n=49) evinced significantly greater numbers of night wakings and longer mean durations of night-waking episodes than their insecure-avoidant counterparts (n=193). Moreover, infants with insecure-resistant attachments were more likely than infants with insecure-avoidant attachments to evince clinically significant sleep problems. To explain our findings we suggest a special role for REM sleep in development of sleep problems and of emotional regulation vis a vis the mother.