Infant bedtime and bedtime variability are independently associated with total sleep duration

We examined the relationships among infants' bedtime, bedtime regularity, total sleep time, night awakenings and sleep latency in infants over the course of one month, utilizing subjective and objective sleep data 

Maristella Lucchini, Shambhavi Takur, Monica R. Ordway, Natalie Barnett

Presented at SLEEP 2024


Sleep-related behaviors in the realm of pediatrics encompass elements that facilitate sleep, such as a regular sleep schedule, following a bedtime routine, and positive parent-child interactions before bedtime. Several studies have shown a positive association between an early bedtime, consistent routines and parent-infant interaction promoting infant independence in falling asleep with longer sleep duration and less night awakenings. Nonetheless, few studies have investigated bedtime regularity. Thus, we examined the relationships among infants' bedtime, bedtime regularity, total sleep time, night awakenings and sleep latency in infants over the course of one month, utilizing subjective and objective sleep data. 


We recruited 253 infants 4-11 months old (mean 6.7±2 months), 46% males. Parents completed surveys on socio-demographic information and the Brief Infant Sleep Questionnaire-Revised (BISQ-R). Objective sleep measures including average bedtime (BT), total sleep time (TST), number of night awakenings (NA) and the standard deviation for bedtime (BTV), were collected for one month using Nanit auto-videosomography (mean 24±5.3 nights). Linear and logistic regressions modeled the relationship between BT and BTV as predictors of objective metrics of TST and NA and sleep latency collected from the BISQ-R. Infant’s sex and age were included as covariates. 


Compared to a BTV of 15 minutes or less, a BTV of 45 minutes to 1 hour was associated with a TST shorter by 28.0±10.2minutes, and a BTV of more than 1 hour to TST shorter by 33.5±11.8min. Compared to a BT before 7pm, later BT was associated with a shorter TST. Specifically, TST was 19.7±10 min (p=0.03) less when BT was between 7-8PM, 63.8±10.0 min (p< 0.001) less for BT at 8-9PM, and 126.4±12.7 min (p< 0.001) less when BT was after 9PM. NA were not associated with BT or BTV. BT was associated with sleep latency, with infants going to bed after 9pm being more likely to take more than 16 min to fall asleep compared t o infants going to bed before 7pm (OR 9.9 CI 1.22-80.4,p=0.03). 


Higher BTV and BT after 7PM were independently associated with shorter TST in infants. These results provide important information for clinical practice and further work should explore how to incorporate this information in sleep interventions.

About the researchers

The authors included Maristella Lucchini, Shambhavi Takur, Monica R. Ordway, and Natalie Barnett. 

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  • Dr. Maristella Lucchini serves as Senior Clinical Researcher at Nanit. In her role, Maristella works to secure grant funding in collaboration with Nanit’s university research partners and supports the development of the company’s research collaborations around the world. Previously, Maristella served as an Assistant Research Scientist in the Division of Developmental Neuroscience, Department of Psychiatry at Columbia University Irving Medical Center where she led projects across several cohorts focusing on sleep health for pregnant and postpartum women and their children. Maristella’s research focused on underserved communities and sleep health disparities in the perinatal period. During her years as a postdoctoral researcher at Columbia University Irving Medical Center in the Department of Psychiatry, Maristella was selected to participate in the American Academy of Sleep Medicine Young Investigator Research Forum. She holds a Ph.D. in Biomedical Engineering from Politecnico di Milano.

  • Shambhavi Thakur serves as Clinical Research Data Analyst at Nanit. She holds a Masters degree in Health Informatics and Life Sciences. She oversees the research collaborations with various universities and analyzes sleep data for internal as well as external studies.

  • Dr. Monica Ordway’s NIH-funded program of research is focused on the understanding of the biosocial relationships that determine health and development in early childhood. Her expertise in community-based participatory research, innovative and non-invasive biomarkers of stress, and objective sleep measurement has helped to generate new knowledge about the role of the multidimensional constructs of sleep health in mitigating the risk of toxic stress among infants and toddlers who experience adversity. Prior to completing her PhD and a postdoctoral fellowship at Yale University, she worked as a primary care pediatric nurse practitioner for 10 years in a large urban practice. She continues to work as a nurse practitioner at the Yale Pediatric Sleep Clinic.

  • Dr. Natalie Barnett serves as VP of Clinical Research at Nanit. Natalie initiated sleep research collaborations at Nanit and in her current role, Natalie oversees collaborations with researchers at hospitals and universities around the world who use the Nanit camera to better understand pediatric sleep and leads the internal sleep and development research programs at Nanit. Natalie holds a Ph.D. in Genetics from the University of New England in Australia and a Postgraduate Certificate in Pediatric Sleep Science from the University of Western Australia. Natalie was an Assistant Professor in the Neurogenetics Unit at NYU School of Medicine prior to joining Nanit. Natalie is also the voice of Nanit's science-backed, personalized sleep tips delivered to users throughout their baby's first few years.

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