Behavior associated with sleep & immunity in space: Psychoneuroimmunology in head down tilt bedrest (preliminary data from campaigns 1 and 2)

Kurzfassung

INTRODUCTION This study is a supplement to out group’s CIPHER-BASIS and CIPHER-BASIS-PNI studies and seeks to accelerate the identification and characterization of psychoneuroimmunological interactions that contribute to risks of adverse cognitive/behavioral conditions or mental disorders during exploration class missions. During such missions, the crew members will be exposed to numerous stressors including prolonged periods of isolation, confinement, environmental extremes, operational demands, and psychosocial challenges. One of the acutely visible and persistent signs of microgravity-induced cephalad fluid shift is facial edema and deformation that consequently reduces an individual’s facial expressiveness and capacity to convey non-verbal affective cues. Since facial expression of affective content presents a fundamental aspect of social interaction and maintenance of interpersonal relations, any changes or limitations in this capacity during spaceflight could exacerbate the negative communication or psychological effects of isolation and confinement, contributing to the risk of developing behavioral or psychiatric disorders (BMed). Sustained exposure to psychological stressors, confinement, and isolation are all known to reduce immune competency and promote systemic inflammation and alter facial expressiveness on Earth and in spaceflight. It remains unknown whether spaceflight-relevant isolation, confinement, and exposure to operational stressors such as headward fluid shifts (simulated by head-down tilt exposure) and deconditioning (simulated by bedrest) are associated with inflammation-mediated changes in neurocognitive function and affective processing in the astronaut-like population, nor how these neurocognitive deficits may affect the ability of crewmembers to interpret each-others’ altered facial expressiveness due to microgravity-induced facial edema. The goal of this project is therefore to characterize the relationship between perceived emotional valence of previously recorded facial expression photographs—collected in head up/head down tilt—and immune function before, during, and after exposure to 60-day head down tilt bedrest (HDBR) conducted at DLR :envihab facility. METHODS To achieve the stated goal, we will complete the following specific aims. Specific Aim 1: Characterize the relationship between perceived emotional valence from facial images at varying degrees of HUT/HDT (Spaceflight Analog Facial Emotion Recognition, SAFER)—before, during, and after exposure to :envihab bedrest. Samples will be collected before (BDC-12 to BDC-1 time window), during (HDT12/HDT45 to HDT50/HDT60 time window), and after (R+0 and R+15 window) DLR/:envihab bedrest campaigns between 2024 and 2027. Neurobehavioral measures will include surveys for assessment of facial emotional recognition (SAFER), anxiety (STAI), sleep quality/duration (PSQI), as ell as Standard Measures for Bedrest (PANAS, GHQ), and Cognition battery. Specific Aim 2: Characterize the relationship between perceived emotional valence from facial images at varying degrees of HUT/HDT (SAFER), stress and immune function biomarkers—before and after exposure to :envihab bedrest. Stress and immune response measures will be used in conjunction with psychometric data. Plasma samples from all the subjects will also be analyzed in duplicate for cytokines and biomarkers of inflammation and stress including cortisol, DHEA-S, epinephrine, norepinephrine, dopamine, alpha amylase, lysozyme, and chromogranin (NULISA-seq); All saliva samples will be collected using the non-invasive commercially-available Salimetrics polyester Oral Swab (SOS) technology (Salimetrics, CA, USA) which has been validated for the measurement of salivary hormones, sIgA and alpha-amylase. RESULTS As of December 2025, we have completed data collection on n=23 subjects (32±5 years of age, 64% female) in DLR/:envihab HDT BR campaigns 1 and 2. Our team is continuing to coordinate with colleagues at DLR/:envihab as well as NASA JSC and LSU to ensure preparation for Campaign 3, as well as seamless data collection, analysis and interpretation. We are in the process of analyzing full data sets from Campaigns 1 and 2, and will be presenting it at the time of the conference. DISCUSSION Findings from this study will further characterize the effects of HDT bedrest on neurobehavioral and immunological function, and thus directly contribute to identification of key threats to behavioral health, development of measures for monitoring behavioral health, and understanding interactions between immune, psychological and perceptual factors in behavioral health associated with long duration missions. By using the SAFER survey – developed as a part of the BASIS-PNI project and tested in HERA, this study will further validate this measure in another spaceflight analog – HDT BR – thus expanding available tools for assessment of health and human performance in spaceflight.