Shorter nighttime sleep in Asian infants can’t be explained by socioeconomic factors alone.

Interview by Bushraa Khatib

Parent reports of their children’s sleep duration differ by race and ethnicity,^1,2 but it is important to know if these differences could be measured objectively, says Susan Redline, MD, MPH, a professor of sleep medicine at Harvard Medical School and professor of epidemiology at T.H. Chan Harvard School of Public Health. She also notes that Black, Hispanic, and Asian adults have been observed to sleep less than white adults.³ The trends prompted her to explore sleep duration in infants by race and socioeconomic status in a study published in Sleep. “We wanted to know if differences in sleep manifest early in life,” she says.

The research team used ankle-placed actigraphs to measure sleep across a 24-hour period in infants at ages one month and six months. They found that although nighttime sleep lengthened and became more consolidated during the first six months of life, patterns of daytime and nighttime sleep varied among infants from different racial and ethnic backgrounds. 

“Daytime sleep was longer in Black and Latino children compared to white and Asian children at both one and six months old. However, nighttime sleep increased less in minority infants compared to white infants between one and six months of age,” Redline says. “Specifically, at six months old, nighttime sleep was shorter by approximately 30 to 40 minutes in Black, Latino, and Asian infants compared to white infants.”

Redline says low socioeconomic status was also associated with lower nighttime sleep at six months of age. “Considering socioeconomic factors markedly reduced the observed race/ethnic differences in sleep of Black and Latino compared to white children,” Redline says. “However, Asian children had shorter nighttime sleep and more awakenings compared to white children even in analyses that adjusted for socioeconomic factors.” 

[Editor’s Note: Read the full study, Emergence of racial/ethnic and socioeconomic differences inobjectively measured sleep–wake patterns in early infancy: results of the Rise & SHINE study, in Sleep.]

Redline discussed the study with Sleep Review over email. The transcript has been lightly edited for clarity and style.

[RELATED: Study of Infants: Sleep Differences by Race & Income Emerge Early]

What are the advantages of using actigraphy along with parent reporting as opposed to parent reporting alone?

SR: Actigraphy is an objective measure which is not influenced by parental differences in reporting. It also can quantify the timing of sleep and frequency of waking bouts.

What surprised you?

SR: The finding of more frequent awakenings in Asian children.

Why do you think Asian infants had more frequent night awakenings and less night sleep compared to white infants?

SR: We don’t know. However, they possibly relate to differences in feeding or bedtime practices, parental stress, or exposures to light or other environmental factors.

How might the relatively small sample size of African American and Asian mothers affect findings?

SR: The small samples can lead to imprecision of our estimates—the associations may be smaller or larger than we saw. Also, our findings were based on a sample of families from the greater Boston area and may not generalize to families in other geographic areas.

Did you find anything interesting in the relationship between breastfeeding and bed-sharing on sleep duration?

SR: We did not find that these factors explained the differences in sleep but we need to look more closely at these factors in larger studies.

What are your thoughts on the benefits of nighttime versus daytime sleep and vice versa in infants this age?

SR: This is an open question. Some data indicate that there may be benefits of daytime sleep while other studies suggest that it is nighttime sleep that is most important for development.

What are the clinical implications of your research?

SR: Clinicians may want to specifically address sleep-related behaviors and sleep environmental conditions of infants in families with lower socioeconomic status and help those families identify optimal strategies for maximizing nighttime sleep.

What further research should be done?

SR: There needs to be further research identifying the specific factors associated with socioeconomic status and family backgrounds that influence infant sleep. Longitudinal follow-up to track how sleep further changes across children and associates with health are important.

The Study:

Xinting Yu, Mirja Quante, Michael Rueschman, et al. Emergence of racial/ethnic and socioeconomic differences in objectively measured sleep–wake patterns in early infancy: results of the Rise & SHINE study. Sleep. 2021 Mar 12;44(3):zsaa193.

References

1. Taveras EM, Gillman MW, Kleinman K, et al. Racial/ethnic differences in early life risk factors for childhood obesity. Pediatrics. 2010 Apr;125(4):686-95. 

2. Carnethon MR, De Chavez PJ, Zee PC, et al. Disparities in sleep characteristics by race/ethnicity in a population-based sample: Chicago Area Sleep Study. Sleep Med. 2016 Feb;18:50-5.

3.  Xiaoli Chen 1, Rui Wang 2, Phyllis Zee, et al. Racial/ethnic differences in sleep disturbances: The multi-ethnic study of atherosclerosis (MESA). Sleep. 2015 Jun 1;38(6):877-88.

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Sleep researchers interested in participating in a Q&A should email editor[at]sleepreviewmag.com with a link to their relevant study.