Tuesday 7 July 2009

Babies and circadian rythm.

The hormone Melatonin produced in the pineal gland regulates sleep. It does so using the initial building block of tryptophan which is an omega 3 fatty acid. This initial and important building block is present in breast milk. Mum's circadian rythm is usually well established and it is interesting that a study looking at the levels of this important omega 3 in breast milk has found that mum's circadian rythm has an effect on the amount of "sleep related hormone" secreted in breast milk.
Sleep efficiency in babies of 12 weeks, both only breast fed and those who were formula fed was measured over a week and it was found that assumed sleep, actual sleep and sleep efficiency was significantly better in exclusively breast fed babies.
It follows that breast fed babies are already learning to develop a circadian rythm which is parallel to that of mum. The levels of tryptophan which fluctuate to follow mum's rythm are starting to "train" baby.

Another study investigated the relationship between exposure to light and 24-h patterns of sleep and crying in young, healthy, full-term babies living at home and following a normal domestic routine. Babies were monitored across three consecutive days at 6, 9 and 12 weeks of age. There was an early evening peak in crying which was associated with reduced sleep at 6 weeks. Across the trials there was a gradual shift towards a greater proportion of sleep occurring at night. Sleeping well at 6 weeks was a good indication of more night-time sleep at 9 and 12 weeks. Babies who slept well at night were exposed to significantly more light in the early afternoon period. These data suggest that light in the normal domestic setting influences the development of the circadian system.

Both of these studies demonstrate the ability of babies to "learn" a circadian rythm and confirm that encouraging naps in normal daylight will improve infants night sleep patterns.

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