0136 Diurnal Patterns in Suicidal Thinking Among Young Adults

Abstract Introduction Suicide is the second-leading cause of death among young adults. Disrupted sleep and circadian rhythms may contribute to the risk of suicide in this age group. Nocturnal wakefulness, for example, may create changes in brain function that contribute to increased incidence of suicide. However, there are limited data on whether suicidal cognitions vary across the day. Methods A sample of N=143 individuals aged 18-25 were recruited to participate in a week-long ecological momentary assessment study of sleep and suicidal thoughts. Sleep was sampled daily using a sleep diary, and suicide-related cognitions were sampled five times per day using automated text messages. Text surveys were scheduled across 24 hours (roughly at 2AM, 7AM, 12PM, 5PM and 10PM) and grouped into 6-hour bins (2300-0459, 0500-1059, 1100-1659, 1700-2259). Individuals with unusual or elevated levels of suicidal ideation were followed-up by study personnel for safety. Results A total of N=3442 text surveys were collected from N=134 participants. Participants provided an average of 26 surveys each (SD=8.3). A total of N=93 (2.8%) of surveys reported suicidal ideation. As a proportion of all surveys, suicidal ideation was most prevalent from 2300-0459 (N=18, 3.2%) and least from 0500-1059 (N=20, 2.2%). Among suicidal ideators, the desire to die was most elevated from 1100-1659 (1.8 out of 4, SD = 1.19), the intention to die was greatest from 1100-1659 (0.9 out of 3, SD=0.8), and the ability to resist the urge to die was lowest in the 0500-1059 (3.1 out of 4, SD=1.12). However, there were no statistical differences across time categories for the presence of suicidal ideation or severity/intensity of these thoughts. Conclusion Suicidal ideation was measured in nearly every hour of the 24-hour day, and severity of suicidal ideation appeared to fluctuate over time. Nevertheless, the presence of suicidal ideation and its severity did not differ statistically across the day, likely due to the small number of reported suicidal cognitions across the sample. Additional work will examine how sleep continuity and/or regularity may influence these findings. Support (if any)