Background: Despite the high prevalence of suicidal ideation (SI) among adolescents, the identification of factors that predict acute increases in SI remains a major challenge in the field of psychiatry. Changes in sleep during adolescence may represent both a general risk mechanism and a marker of acutely increased risk for suicide. Social jetlag (SJL), which refers to a discrepancy in sleep patterns between school nights and weekend nights, peaks during adolescence. Although both girls and boys experience SJL during adolescence, sex differences may confer distinct pathways for suicide risk. Sex hormones play an important role in the regulation of circadian rhythm and sleep-wake cycles. In particular, variation in hormone levels across the menstrual cycle influences the ability to maintain sleep-wake cycles following sleep restriction.
Both SI and sleep-wake patterns vary across the menstrual cycle. However, no study to date has examined the potential link between menstrual phase, sleep, and SI. Therefore, the goal of the proposed study is to examine whether irregular sleep-wake patterns, described as SJL, (a) are associated with between-subjects differences in severity of SI, and/or (b) precede acute increases in severity of SI within-subjects. We will also examine whether the association between SJL and SI is highest during specific phases of the menstrual cycle.
Methods: We will recruit forty adolescent females, ages 12-17, from Stanford hospitals and associated clinics. All participants must experience current SI (>=31 within the past two weeks on the Suicidal Ideation Questionnaire-Junior) and must be post-menarche (must have had their first period). Starting on the first day of their next menstrual period, participants will wear an actigraph (a device that looks like a wristwatch and measures sleep-wake patterns) contiguously for the duration of their menstrual cycle, and will complete short daily questionnaires about perceived sleep quality and SI. Levels of estradiol, a sex hormone linked to sleep and SI, will be measured via saliva samples, taken once per week over the approximately four weeks of the study.
Hypotheses: (H1): Girls with more severe SJL will experience more severe SI. (H2a): More severe SJL over the prior seven days will predict higher SI on the 8th day. (H2b): The association between seven-day SJL and eighth-day SI will be highest during the perimenstrual phase. (H3, exploratory): The association between SJL and SI will be highest when estradiol is lowest.
Resources: Our laboratory has developed best practices for encouraging compliance and maintaining engagement during collection of actigraphy data and daily self-report questionnaires over a period of 21 days. We have also established a recruitment pipeline through Stanford hospitals and two outpatient clinics directed by Co-Investigator Dr. Berk. Additional resources available at no cost to the current award include five actigraphs, customized daily survey software, a part-time research coordinator, and a part-time research assistant.
Significance: The proposed research could (a) identify a risk factor for acute increases in SI, (b) elucidate a mechanism that contributes to sex differences in SI, and (c) identify SJL as a target for intervention to reduce SI.
