Acute Stress Reaction

The goal of this clinical trial is to find out if vitamin D supplements help healthy adults maintain their cognitive and simple physical task performance and emotional state during highly stressful situations. The main question it aims to answer is: \- Does vitamin D help maintain cognitive and physical task performance and emotional state during highly stressful situations? Researchers will compare vitamin D to placebo (a look-alike tablet that contains no active ingredients) to see if vitamin D better maintain cognitive and physical task performance and emotional state during highly stressful situations. Participants will: * Take vitamin D or placebo tablets daily for 8 weeks. * Perform cognitive and simple physical tasks and rate their emotional state under highly stressful situations. * Wear a stress belt that delivers mild electric shocks 1 - 5 times while participants are performing laboratory tasks. * Wear a wristwatch-shaped activity monitor for 9 weeks. * Visit the laboratory 5 times.

This clinical trial aims to evaluate the nature and duration of effects of three FDA-approved medications (propranolol and hydrocortisone) on military-relevant cognitive, emotional, and motor performance following an exposure to a stressful situation (i.e., exposure to a tarantula) in physically healthy adult volunteers (aged 18 - 40) with fear of spiders to help the future development of medications for treating Acute Stress Reactions. The main questions this study aims to answer are: Will placebo treatment (oral placebo) result in significant decrements in Psychomotor Vigilance Task (PVT) performance compared to propranolol treatment? Will placebo treatment \[intramuscular (IM) placebo\] result in significant decrements in PVT performance compared to hydrocortisone treatment? Participants will receive one of five study medications (oral propranolol, oral placebo, IM hydrocortisone, or IM placebo) after a brief exposure to a tarantula. Participants will complete cognitive and simple motor tasks and psychological assessments before and after the study medication administration.

This study investigates whether the psychophysiological benefits of breathing exercises are driven by a specific physiological rhythm (6 breaths per minute) or by the general psychological experience of performing a structured, mindful activity. Researchers aim to determine if "coherent breathing", which is hypothesized to synchronize heart and respiratory rhythms, offers unique physiological protection against stress compared to breathing at a natural pace or simple resting. The main questions it aims to answer are: * Does slow, steady breathing at 6 breaths per minute lower physical stress markers (like heart rate variability and cortisol) better than faster, but structured breathing or just sitting still? * Is the calming effect caused by the specific breathing rhythm or simply by performing a structured, relaxing activity? Researchers will compare three groups to see if the specific rhythm of "coherent breathing" offers unique benefits: 1. Group (Interventional): Coherent Breathing: Slow breathing at 6 breaths per minute. 2. Group (Sham Breathing): Regular breathing at 15 breaths per minute (matching a natural pace). 3. Spontaneous Breathing (Control Group): Natural, unguided breathing. Participants will: * Complete a one-day preparation phase to become familiar with the breathing technique. * Visit the research center for one experimental session. * Perform their assigned breathing method before and after a stress test. * Take the Maastricht Acute Stress Test (MAST), which involves putting a hand in cold water and doing mental math. * Provide saliva samples and have their heart rate variability, and mood measured multiple times.

This study will examine the safety and efficacy of BXCL501 to reduce ASR symptoms and behavioral changes among patients presenting to the Emergency Department (ED) after Motor Vehicle Collision (MVC). Specifically, the investigators will perform the BXCL501 (BASIS) Trial, a double-blind placebo-controlled Randomized Controlled Trial (RCT) to determine if BXCL501 (dexmedetomidine hydrochloride sublingual film) initiated in the ED in the hours after MVC to high risk individuals, treats/reduces ASR/ASD symptoms (primary outcome), improves neurocognitive function, and prevents/reduces posttraumatic stress (PTS) symptoms (secondary outcomes) long term. 100 participants will be randomized, receive study drug in ED and be discharged with a 2-week drug supply. Prior to initial dose of study drug administration, and during the hours, days, and weeks after participants will receive serial longitudinal assessments of psychological and somatic symptoms, neurocognitive function, and adverse events.

This study will examine the safety and efficacy of TNX-102 SL to reduce ASR symptoms and behavioral changes among patients presenting to the emergency department (ED) after motor vehicle collision (MVC). Specifically, the investigators will perform the Optimizing Acute Stress reaction Interventions with TNX-102 SL (OASIS) Trial, a double-blind placebo-controlled randomized clinical trial (RCT) to determine if TNX-102 SL initiated in the ED in the hours after MVC to high risk individuals, treats/reduces acute stress reaction (ASR)/acute stress disorder (ASD) symptoms (primary outcome), improves neurocognitive function, and prevents/reduces posttraumatic stress (PTS) symptoms (secondary outcomes) long term. 180 participants will be randomized, receive study drug in ED and be discharged with a 2-week drug supply. Prior to initial dose of study drug administration, and during the hours, days, and weeks after participants will receive serial longitudinal assessments of psychological and somatic symptoms, neurocognitive function, and adverse events.

This Open-Label, Non-Randomized Clinical Study involving 280 participants who will undergo a total participation of 6 hours.

The iCOVER intervention was developed to rapidly restore functioning in individuals experiencing an Acute Stress Reaction (ASR). iCOVER is undergoing widespread adoption but has not been tested for efficacy. iCOVER was designed to be administered by peers, paraprofessionals, or medical personnel in 60-120 seconds, including in military operational environments. The term iCOVER is an acronym that summarizes the six specific steps of the intervention: (1) identify that an individual is experiencing an ASR; (2) Connect with the individual through word, eye contact, and physical touch to draw them back to the present moment; (3) Offer commitment so that the individual feels less psychologically isolated and withdrawn (e.g., "I'm right here with you"); (4) Verify facts - ask simple fact-based questions to engage the individual in deliberate cognitive activity; (5) Establish order of events - briefly review what has happened, what is happening, and what will happen to orient the individual; and (6) Request action to re-engage the individual in purposeful behavior. Participants will be randomly assigned to one of three groups: iCOVER, usual care, or physical presence with reassurance. Investigators have elected to use two different control conditions, in order to examine the reliability of the iCOVER intervention in comparison with two typical responses to individuals experiencing an ASR (i.e., physical presence with reassurance, no specific treatment).

The aim of this study is to determine the effects of regular cannabidiol (CBD) use on the psychobiological mechanisms of the stress response. This will be achieved by comparing acute stress responses of adults who either use or do not use CBD regularly. Correlates of CBD use, including tobacco use, will be collected.