Improvements in sleep indices during exam stress due to consumption of a Bifidobacterium longum .
Level 2 - randomized trial
Randomized, placebo-controlled crossover trial in humans.
PubMed 34589719 · doi:10.1016/j.bbih.2020.100174
What was done
A randomized, placebo-controlled, repeated-measures crossover study evaluated the effects of *Bifidobacterium longum* 1714 on stress, mood, sleep, and cognitive function. Twenty healthy male university students underwent testing during an academic exam period, which served as a naturalistic chronic stressor. Outcomes included self-reported questionnaires for stress, depression, sleep quality, physical activity, gastrointestinal symptoms, cognition, and mood, alongside computerized cognitive testing via the Cambridge Neuropsychological Test Automated Battery (CANTAB).
What was found
Stress and depression scores increased during the exam period in both the probiotic and placebo arms. The abstract reports no exact numerical values, confidence intervals, or p-values. It notes that *B. longum* 1714 significantly improved overall sleep quality and sleep duration compared with placebo during exam stress. However, the probiotic showed no efficacy compared to placebo in altering measures of stress, depression, working memory, visual memory, sustained attention, or perception.
Why it matters
This study provides preliminary human evidence that *B. longum* 1714 may help buffer sleep quality and duration against academic stress, though it appears ineffective for concurrent cognitive impairment or mood changes.
Limits
The sample size was very small (n = 20) and restricted entirely to young male university students, limiting generalizability. Sleep parameters were self-reported rather than objectively tracked with polysomnography or actigraphy. The abstract reports no quantitative values or effect sizes, and the intervention failed to show benefits on any cognitive or subjective psychological distress outcomes.
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- partial Bifidobacterium longum 1714 improves the quality of deep sleep.