Native language shifts across sleep-wake states in bilingual sleeptalkers.

STUDY OBJECTIVES To assess language used during episodes of sleeptalking in bilingual children. DESIGN The investigation was accomplished through the parents who, after having received appropriate information, participated by filling out a survey on sleeptalking. SETTINGS The study was performed in three bilingual schools of the Basque country, a region in northern Spain in which two completely different official languages are spoken. PATIENTS A total of 1000 parents agreed to participate, and 681 children were studied. MEASUREMENTS AND RESULTS Sleeptalking was reported by 383 (56.3%) of children (mean age 9 years; range: 3-17). Most individuals used their dominant (i.e., native) language during sleep. However, a minority (< 4%) were found to use their non-dominant language persistently during episodes of sleeptalking. CONCLUSIONS Balanced bilinguals (those who have equal proficiency in both languages) may sleeptalk in either of the two languages. Dominant bilinguals (i.e., having greater proficiency in one language) may preferentially sleeptalk in their dominant language, with immediate past events probably influencing language use in individual subjects on particular nights. Several considerations are postulated as an explanation for the group who systematically exhibited a dominance shift during sleep.