Sleep is fundamental to health, particularly because of its role as a ‘regulator’ of various functions, including mood, cognition and metabolism. Evidence is also mounting for its vital importance to our immune system. In fact, numerous studies have shown that poor sleep quality increases susceptibility to infections. In addition, good sleep is essential from early childhood, for example, Inserm researchers found in June 2021 that too little or too much nighttime sleep duration by age 2 is associated with a risk of increased wear of glasses by age 5. This time, researchers from the same institute looked at the benefits of sleep on the immunity of youngsters in a study published in the journal Brain, Behavior, & Immunity – Health.
The scientific team started from the observation that studies in adults show a link between lack of sleep and increased levels of certain cytokines, inflammatory molecules whose excess is linked to various diseases such as obesity, diabetes, atherosclerosis, rheumatoid arthritis or depression. However, there is little data on young children as it is known that “ the results achieved in adults cannot be transferred to them due to the clearly different sleep rhythms. ‘ she specifies. Therefore, it was necessary to fill this gap by working from the EDEN cohort, which focuses on child psychomotor development and health. Their goal: to determine the factors that play out during childhood and are likely to influence health in adulthood.
Short or variable sleep promotes elevated levels of certain cytokines
Between 2003 and 2006, women were recruited before the 24th week of pregnancy. They gave birth to 1,899 children followed by childbirth via data collection conducted four times at the first year of life and then at ages 2, 3 and 5 years. This data includes daily sleep durations reported by parents using questionnaires. The researchers thus identified five evolutionary trajectories of sleep between 2 and 5 years of age: short sleep (<10:30 a.m./night), medium to low sleep (10:30–11:00 a.m./night), medium to high sleep (11: 30 p.m./night). night), long sleep (≥ 11:30 h/night) and variable sleep. The data show that the persecuted children were more likely to belong to category two (47.8% of the sample) than to category three (37.2%) and the last category (5.6%).
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The researchers selected 687 children who were tested for multiple cytokines (IL-6, IL-10, INF-γ, TNF-α) at age 5 in another study. The results obtained show that a shorter or alternating sleep duration between 2 and 5 years is associated with increased levels of IL-6-type cytokines and TNF-α at the age of 5 years. And this is independent of other parameters that can influence sleep and cytokine levels, such as gender, gestational age at birth, length of breastfeeding, body mass index (BMI), allergies, antibiotic use, physical activity or eating habits. In contrast, no association was observed between sleep duration and IL-10 or IFN-γ cytokine levels.
Sleep duration: the importance of adhering to official recommendations
« This study does not establish a causal relationship, but suggests that sleep patterns from preschool age may have an impact on serum levels of certain pro-inflammatory cytokines. “, explains Sabine Plancoulaine from the Center for Research in Epidemiology and Statistics in Paris. ” However, a cumulative effect during life combined with other environmental factors could cause the onset of later health problems. This work once again moves in the direction of respecting sleep duration recommendations at all ages, starting from infancy. ‘ she concludes. Further work by the scientific team will consist of confirming these results in another cohort of children and clarifying the role of sleep in their development and subsequent health.
Still, this study is an opportunity for the body to remember the recommended amount of sleep based on age. For newborns aged 0 to 3 months, Inserm recommends 14 to 17 hours of sleep over a 24 hour period. An essential rest because it allows the maturation of the brain. For infants from 4 to 11 months, the sleep duration is between 12 and 15 hours, since it is known that between 6 and 24 months “lSleep changes again to get closer to its final form. “, emphasizes the health insurance company on this subject. Babies from 1 to 2 years old should sleep between 11 and 14 hours, while for preschoolers from 3 to 5 years old, when nap time becomes shorter, the optimal sleep time is 10 to 13 hours. After all, school children aged 6 to 13 need to sleep between 9 and 11 hours a night.