The goal of this study is to learn about a new, real-time, smartphone-based intervention aimed to decrease risk for suicide in adults who have been hospitalized for suicidal thoughts or behaviors. The main questions the investigators aim to answer are:

• Is a real-time, smartphone-based intervention that promotes the use of safety plans and other coping strategies for suicidal thoughts feasible and acceptable?
• Does the real-time intervention result in increased use of safety plans and other coping strategies, and reduce suicidal thoughts?

Participants will:

• Answer questions about current suicidal thoughts on their smartphone up to 6 times each day while they are in the hospital and during the 4 weeks after they leave the hospital
• When they report elevated suicidal thoughts on a smartphone survey, be randomly assigned to receive or not receive automated, interactive reminders to use content from their personalized safety plan or general coping strategies
• Answer brief follow-up questions on their smartphone within a couple hours of receiving or not receiving automated reminders
• Give feedback on their experience with the real-time intervention

Effective, scalable interventions for the highest-risk time for suicide - after inpatient psychiatric hospitalization - are urgently needed. The safety planning intervention (Stanley & Brown, 2012) involves developing a personalized list of prioritized coping strategies for suicidal crises, and has been shown to prevent suicidal behavior (e.g., Nuij et al., 2021). However, roughly 40% of patients with a safety plan never use it (Stanley et al., 2016). The safety plan also includes multiple components (e.g., different internal coping strategies, seeking social support), yet little is known about the internal and external contexts that may impact the accessibility and effectiveness of individual safety plan components. Improving both the ability to promote safety plan use when needed and the understanding of when specific coping strategies are most accessible and effective has the potential to optimize this already evidence-based intervention.

The aim of this study is to leverage the recent micro-randomized trial (MRT) design (Klasnja et al., 2015) to evaluate the proximal effects of automated, interactive, smartphone-based reminders to implement the safety plan and its coping strategies at different levels of suicidal urges and intent. Twenty-five (N = 25) adults hospitalized for suicidal thoughts or behaviors will undergo an intensive longitudinal monitoring protocol, which includes completing up to six brief smartphone surveys per day that assess momentary suicidal urges and intent on a 0 to 10 scale during hospitalization and the 28 days after discharge. After each post-discharge survey with reported high intensity suicidal urges or moderate intent, participants will be "micro-randomized" to receive either a series of automated interactive intervention messages or no intervention. Whether the message content is personalized (from the individual's safety plan) or general (top-rated from others' safety plans) and the specific coping strategy type(s) recommended will also be randomized. Brief proximal follow-up surveys will assess coping strategy use since the last survey prompting micro-randomization, perceived helpfulness of any coping strategies used, and momentary suicidal urges and intent. Qualitative and quantitative data on acceptability and feasibility will be collected from participants and used to inform future real-time intervention refinements. Preliminary efficacy data will be used to inform the development of future, larger-scale studies and the ultimate development of policies for novel just-in-time adaptive interventions that deliver the right time of support, at the right time, and in the right context, for individuals at risk for suicide.

Inclusion Criteria:

• Experiencing suicidal thoughts as part of their inpatient admission
• Ownership of and access to a smartphone (while on the unit and following discharge)
• Ability to speak and write English fluently

Exclusion Criteria:

• Any factor that impairs the ability to effectively participate in the study (e.g., significant cognitive impairment, intellectual disability, presence of violent behavior, psychotic illness/symptoms determined by the treating clinician to impair ability to understand the study or provide informed consent)
• Failure to correctly answer all true/false questions in the consent form