Evidence is mounting on the importance of sleep from infancy. After establishing a link between sleep and quality of sight at the age of fivean Inserm team has this time shown a correlation with immunity: a short duration of sleep in the first years of life seems to be associated with an increased rate of certain cytokines pro-inflammatory, molecules found in several frequent pathologies in adulthood.
Sleep is fundamental to health. It regulates several functions including mood, cognition, metabolism and immunity. In adults, many studies attest to a link between sleep deficit and increased levels of certain cytokines, inflammatory molecules whose excess is associated with various diseases such as obesity, diabetes, atherosclerosis, rheumatoid arthritis. or even depression. But few data exist in young children, and the results obtained in adults cannot be transposed to them given the marked differences in sleep rhythms. To fill this gap, Sabine Plancoulaine’s team at the Center for Research in Epidemiology and Statistics in Paris* worked from the EDEN cohort.
This is intended to study the pre- and postnatal determinants of the development and health of children. Between 2003 and 2006, women were recruited at the University Hospitals of Nancy and Poitiers before their 24e week of pregnancy. They gave birth to 1,899 children, followed from birth via the collection of socio-demographic and medical data carried out four times during their first year of life and then at 2, 3 and 5 years of age. These data include the daily sleep durations reported by parents using questionnaires. The researchers were thus able to identify five evolutionary trajectories of sleep between 2 and 5 years: short sleep (< 10 h 30/night, 4.9% of the sample), medium-low sleep (10 h 30–11 h 00/night, 47.8%), medium-high sleep (regarding 11:30 a.m./night, 37.2%), long sleep (≥ 11:30 a.m./night, 4.5%), and changeable sleep (5.6 %).
At least two cytokines involved
The scientists selected the children for whom they had assays of several cytokines (IL-6, IL-10, INF-γ, TNF-α), carried out at the age of 5 as part of another study. Their work thus covered 687 children. It shows that a shorter or changing sleep duration between 2 and 5 years is associated with increased levels of IL-6 and TNF-α at the age of 5 years, independently of other parameters likely to impact sleep and cytokine levels (sex, gestational age at birth, duration of breastfeeding, body mass index, allergies, use of antibiotics, level of physical activity or dietary habits, etc.). In contrast, no association between sleep duration and IL-10 or IFN-γ levels was observed.
« This study does not establish a causal link, but it suggests that sleep habits may have an impact on serum levels of certain pro-inflammatory cytokines from preschool ageexplains Sabine Plancoulaine. However, a cumulative effect during life, combined with other environmental factors, might cause the appearance of later health problems. This work goes once once more in the direction of respecting the recommendations on the duration of sleep at all ages, and this from early childhood. “, she concludes. Further work for her will consist of confirming these results in another cohort and clarifying the role of sleep in the development and subsequent health of the child.
What is the recommended sleep duration by age?
| age range | Recommended sleep duration (over 24 hours) |
| Newborns – 0 to 3 months | 2 to 5 p.m. |
| Infants – 4 to 11 months | 12 to 3 p.m. |
| Babies – 1 to 2 years old | 11 a.m. to 2 p.m. |
| Preschoolers – 3 to 5 years old | 10 a.m. to 1 p.m. |
| School-age children – 6 to 13 years old | 9 to 11 a.m. |
| Teenagers – 14 to 17 years old | 8 to 10 hours |
| Adults – 18 to 64 years old | 7 to 9 a.m. |
| Seniors – 65 and over | 7 to 8 hours |
Note :
*unit 1153 Inserm/Paris Cité University/Inrae
Source : M. Radmanish et coll. Sleep duration trajectories associated with levels of specific serum cytokines at age 5 : A longitudinal study in preschoolers from the EDEN birth cohort. Brain Behav Immun Health Accessed 2022 Feb 8. DOI: 10.1016/j.bbih.2022.100429
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