Nevertheless, there is little information on whether the development of melatonin production in infants is seasonally regulated. The ontogeny of melatonin production has been extensively studied 7 — The urinary metabolite of melatonin, 6-sulfatoxymelatonin 6SMT , has been proven to be a very reliable index of melatonin production in humans including infants Using a diaper extraction method, it has recently been shown that daily rhythmic 6SMT excretion appeared at 9 to 12 wk of age in full-term infants and at the corresponding postconception age in premature infants 7 , 8.
The latter report, which implied that there were no significant seasonal variations in melatonin production at 12 wk of age, has led to the suggestion that the ontogeny of melatonin in infants does not depend on season. The evaluation of melatonin production in infants as a clinical and diagnostic marker of child development is, however, limited by the lack of a definition of the normal range of melatonin for a given age group.
The purpose of the present study was to establish the normal range of nocturnal 6SMT excretion in full-term infants at 8 and 16 wk of age using a large sample of healthy infants. In addition, we sought to reassess whether the production of melatonin in infants depends on season. This was achieved using a recently developed method 6 for extraction of the urinary components from disposable diapers and for determination of 6SMT content by ELISA.
Because human milk contains some melatonin and, in addition, a pronounced circadian rhythm in melatonin content in human milk has been reported 12 , we examined whether melatonin production in the infants was influenced by their being breast- or bottle-fed at the time of assessment. Due to practical reasons ease of implementation in the clinic and better compliance of the caregivers , we have concentrated on the determination of nocturnal values of 6SMT excretion.
This would be meaningful only if the 6SMT excreted during the nocturnal period out of the entire h period is a constant fraction. To examine this hypothesis, we performed a control study on the diurnal rhythm of 6SMT excretion in a group of 35 8-wk-old infants and determined the ratio of the nocturnal to h 6SMT excretion during both the winter and summer periods.
The nocturnal urinary excretion profile of 6SMT over a h period — was assessed in full-term infants at the age of 8 wk males and females and in 93 infants 55 males and 38 females at the age of 16 wk. In addition, the h daily rhythm of urinary excretion of 6SMT was studied in 35 full-term healthy infants at the age of 8 wk 16 males and 19 females. The study infants were recruited from the infant population that visited the well-baby clinics in the city of Tel Aviv for routine periodical medical examination and immunizations.
The study was approved by the local institutional review board and informed consent was obtained from all parents following a detailed explanation of the nature of the study. Parents were instructed to retain all diapers used by the infant during the nighttime — infants or a h period 35 infants , remove fecal matter, wrap each diaper in a separate, numbered zip-lock bag that was supplied to the parents, and mark the time each diaper was changed. In this study, we focused on determining the total amount of 6SMT excretion during the night.
Therefore, it was unnecessary to enforce fixed diaper exchange intervals during the night, hence, the rate of diaper change was habitual. The diaper-containing bags were transferred to the laboratory within 20 h of collection. To enhance compliance, no instructions were given to the parents regarding the lighting conditions for the infants while sleeping at night.
Some variability may exist in lighting conditions in individual homes that may have increased the variability in individual 6SMT excretion values. Nevertheless, it was assumed that the variability in lighting conditions in individual homes would average across a large study cohort, because lifestyle of families with small babies is not very variable, especially during weekdays. In addition, it is customary for the light intensity in homes in Israel to be dim, less then 10 lux.
To minimize the influence of lifestyle changes due to weekends, all studies were performed between two working days Mondays to Thursdays in the subjects' homes and no diaper collections were performed during the weekend. Briefly, on receipt in the laboratory, the diapers were weighed and net urine weight calculated from the difference between the total weight and the weight of an unused diaper of the same brand.
Samples of the wet diaper pulpy lining were removed by forceps, weighed approximately mg each and macerated in 1 mL methanol. The urine content of the sample was calculated from the difference between the weight of sample and the dry resin weight. The urine extracts were further diluted with buffer to obtain values readable from the standard curves and the 6SMT content determined on a double-blind basis, by an ELISA assay Neurim Pharmaceuticals Ltd.
The validity of this method has been described elsewhere 6. To assess the uniformity of 6SMT recoveries from the diapers, samples were collected from six distinct loci in each of four different infant wet diapers. Mean 6SMT content of each diaper was calculated from the results of the six sampling loci. The diapers were kept at room temperature during this period. The results of these studies indicated that the 6SMT content of the diaper at these times 7.
Kolmogorov-Smirnov test 14 was used to assess the normality of distributions of 6SMT values in the two age groups of infants. The results of the best fit regressions are presented as solid lines in the figures and the values of parameters are given in the text. The difference between the amount of 6SMT excreted nocturnally by infants born during months of short October through March and long April through September days and between infants assessed at winter December through March and summer May through September time was assessed using t tests for independent samples.
Figure 1 represents the h urinary excretion of 6SMT in 35 healthy full-term infants aged 8 wk. Individual urinary excretion rates of 6SMT over 24 h in five full-term infants born between February and March and five full-term infants born between August and September are shown in Figure 2.
Line is a cosine function only used for the purpose of outlining the distribution. The black bar represents the phase used for the assessment of nocturnal 6SMT production. Individual excretion of 6SMT over 24 h in urine collected from five full term infants born in February or March panel A and five full-term infants born during August or September panel B.
The black bars represent the nocturnal phase. The nocturnal excretion of 6SMT in infants aged 8 or 16 wk exhibited a major interindividual variability. Normal 6SMT excretion, defined as 2. A significant rise in ln 6SMT from age 8 to 16 wk was observed 6. Lines are functions only used for the purpose of outlining the two distributions. The nocturnal 6SMT in infants aged 8 wk as a function of month of birth is shown in Figure 4. On average, there was a threefold difference between the mean values of the populations born around the summer and winter solstices.
Line is a cosine function used for the purpose of outlining the distribution. The black bar represents the winter phase; winter and summer solicits are shown as arrows.
Therefore, separate normal values 2. At 8 wk of age, normal 6SMT excretion for short photoperiod infants was 5. Should we start sleep training now that we are home more because of the coronavirus? How can I help my child who has more nightmares than usual since the coronavirus pandemic? Prev item My baby was diagnosed with Pierre Robin sequence. How will this affect his sleep? Next item When will my preemie sleep through the night?
It then remains for about 12 hours until it subsides in the morning. Basically, it regulates our sleep wake cycle. Melatonin is very sensitive to light, and, in some causes, won't be produced at all until you're in a darker environment. The supplement melatonin is often used to help those who have trouble falling asleep or those who fight through their natural melatonin and stay awake too late at night!
In order for us to naturally help melatonin do its job, we need to make sure we are putting our babies to sleep within their natural sleep windows, as well as eliminating light close to bedtime. Another hormone that plays in a role in the quality of sleep is cortisol. This is a stimulating hormone that is mainly related to stress. Everything is new to them now, and you are the only thing that is familiar.
They are going to want to be held, and sometimes that is the only way that they can sleep. This is a question that I get from new moms quite often. Rather than paying attention to how much sleep your infant is getting, it is better to pay attention to the quality of sleep they are getting as well as their growth and development.
Are they growing well e. And I will always tell my patients to follow their gut instinct. If you feel something is wrong with your baby, please seek help from a pediatrician, midwife, or lactation consultant.
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