Biology subjects

Muehlematter, C.

Publications and source records attributed to Muehlematter, C..

3 recordsLinked to original sources

bioRxiv2025

The gut microbiota and sleep in infants: a focus on diurnal rhythmicity patterns

Emerging evidence supports a bidirectional relationship between the gut microbiome and sleep, partly mediated by the microbiota-gut-brain axis. Circadian rhythms appear to influence early developmental processes and may play a role in shaping this relationship. While infancy is a critical window for both gut microbiota establishment and the maturation of sleep regulation, the role of gut bacteria in modulating infant sleep remains poorly understood. In this longitudinal study, we performed continuous within-subject sampling (monitoring across 48 hours) in 20 infants at 2, 4, and 6 months of age to examine associations between the establishment of gut microbiota and sleep patterns. We hypothesized that microbial diversity and sleep rhythmicity would be linked across both short (diurnal) and long (monthly) time scales. Gut microbiota profiles were characterized using 16S rRNA gene sequencing; gut melatonin concentrations were measured; and sleep metrics were quantified through wearable actimetry, parent-reported 24-hour sleep diaries, and the Brief Infant Sleep Questionnaire (BISQ). Parents additionally completed the Baby Care Questionnaire (BCQ), assessing parenting style, and the Ages and Stages Questionnaire (ASQ), evaluating infant behavioral development. In some infants, alpha diversity followed diurnal rhythmic patterns. Although bacterial rhythmicity was not significantly associated with sleep rhythmicity, as quantified with the Circadian Function Index, infants with higher alpha diversity had more robust sleep rhythmicity ({beta}Faith PD= 0.0721, SE = 0.0337). Infant age emerged as the strongest predictor of both gut microbiota diversity (observed features: {beta}age = 0.101, SE = 0.0172) and gut melatonin concentrations ({beta}age = 0.638, SE = 0.162). For the same age, gut microbiota temporal volatility - an indicator for bacterial community instability - was not associated with sleep patterns. This study demonstrates promising short- and long-term links between gut microbiota diversity and sleep-wake rhythm maturation in infancy. Further research is needed to elucidate the mechanistic role of the gut microbiome in sleep development.

microbiology↗

bioRxiv2025

Rhythms of Early Life: Gut Microbiota Rhythmicity and Circadian Maturation in infants

BackgroundThe human gut microbiota undergoes daily fluctuations, yet its interaction with sleep-wake patterns during infancy remains largely uncharted. This study aims to elucidate the relationship between gut microbiota rhythmicity and the development of sleep patterns in infants over the first year of life. We continuously monitored 162 healthy infants across multiple days at 3, 6, and 12 months of age using ankle actigraphy and 24-hour diaries. The Circadian Function Index (CFI) was computed as a proxy for sleep-wake rhythm maturation. Stool samples were collected to profile gut microbiota taxa composition via 16S rRNA gene amplicon sequencing, and microbial oscillations were assessed through sine and cosine fitting to detect 24-hour patterns. ResultsOur findings revealed that the relative abundance of bacterial taxa exhibited rhythmic patterns, with 26 zOTUs (1.74%) following a sine pattern and 100 zOTUs (6.69%) displaying cosine rhythmicity. Cosine rhythmicity became more pronounced with age, showing strong maturation: 7 zOTUs at 3 months, 2 zOTUs at 6 months, and 86 zOTUs at 12 months. Notably, 105 zOTUs (7.02%) were associated with CFI, demonstrating a significant relationship between gut microbiota rhythms and sleep development. Among these, 27 zOTUs with sine dynamics and 96 zOTUs with cosine dynamics were linked to CFI, with this association strengthening as infants aged. ConclusionsThese results highlight the increasing synchronization between gut microbiota rhythmicity and sleep-wake cycles during infancy, pointing to a critical window for potential health interventions. This novel observation, previously reported in rodents and adults, underscores the role of gut microbiota in early human development, offering new avenues for enhancing developmental outcomes through targeted interventions.

developmental biology↗

bioRxiv2024

From womb to crib: How fetal activity patterns in utero reveal postnatal sleep behavior

ImportanceThe human circadian system, a critical biological mechanism governing the sleep-wake cycle, begins to oscillate before birth. Distinct fetal behavioral states have been described using short-duration ultrasound recordings, but the alignment of fetal activity with day and night cycles (i.e., diurnal rhythms) remains poorly understood due to the lack of long-term monitoring. Accordingly, a substantial knowledge gap exists concerning the evolution of fetal diurnal rhythms into infant sleep-wake cycles. ObjectiveTo investigate the development of fetal diurnal rhythms and their evolution into postnatal infant sleep, as well as the role of maternal factors and melatonin in shaping early circadian entrainment. MethodsIn this cohort study, conducted in 2022 and 2023, we collected over 20 000 hours of wearable acceleration and temperature data from 32 fetuses and their mothers during continuous 5-day monitoring in the third trimester of pregnancy. The cohort was subsequently followed longitudinally from the prenatal period through 6 months postpartum, with infant sleep outcomes assessed at three key time points (first postnatal weeks, 3 months, and 6 months) using sleep diaries and questionnaires. The first postnatal assessment additionally included breast milk and infant stool sample collection. ResultsMulti-level modelling revealed early diurnal rhythms in fetuses that align with maternal activity and circadian rhythms. Random Forest analyses identified fetal day/night sleep duration ratio - a simplified proxy for fetal circadian entrainment - as the strongest predictor of postnatal infant sleep, with fetuses preferring nighttime sleep maintaining this preference postnatally. Maternal sleep regularity (i.e., consistent sleep patterns characterized by low day-to-day variability in sleep timing) during pregnancy also predicted infant sleep, associating with a stronger preference for nighttime sleep in infants. Conclusions and relevanceThese findings highlight the potential influence of intrauterine and maternal factors on the evolution of circadian entrainment. Our study contributes to a broader understanding of the earliest emergence of circadian rhythms, supporting future research on their long-term health impacts. Maternal sleep regularity stands out as the earliest modifiable target for interventions, offering an actionable pathway to promote infant circadian entrainment, with potential long-term benefits for family dynamics and well-being.

developmental biology↗