Stress-buffering and Sleep Disturbance-resilient Effects of a Dual Bifidobacterium Longum Combination Under Short-term Travel

Inclusion Criteria: * Willing to participate in this study and able to provide written informed consent before any study procedures are initiated. * Able and willing to comply with all study procedures as required by the protocol, including continuous wearable device use, saliva and stool sample collection, and completion of questionnaire assessments. * Willing to accept randomization and group allocation as determined by the study protocol. Exclusion Criteria: * Known use of antibiotics or systemic corticosteroids within 4 weeks prior to enrollment. * Use of probiotic supplements within 4 weeks prior to enrollment. * Planned use of any probiotic supplements during the study period. * Known history or current presence of major endocrine disorders, active inflammatory bowel disease or other severe gastrointestinal diseases, or severe sleep disorders requiring treatment adjustment. * Pregnant or intend to get pregnant, or lactating women. * Known allergy to any probiotic products. * Participation in any other clinical interventional study involving drugs, dietary supplements, probiotics, or prebiotics within the past three months. * Or those who, according to the researcher's judgment, may have inadequate adherence or are unable to complete the study protocol.