The Development of Circadian Rhythms in Human Infants

2 Methods
2.1 Overview of recruitment for study
The aim of the study was to investigate the normal development of the circadian
rhythms in human infants. Deep body temperature during night time sleep was used
as a measure of physiological development during the first postnatal months of life.
Changes in the secretion of melatonin with age were measured using urinary
estimation of the metabolite 6-sulphatoxymelatonin (aMT6s). Cortisol secretion was
measured in urine. Paired infant maternal activity-rest actigraphy elucidated night-
time sleep patterns. Finally the pattern of expression of peripheral genes was
examined by extracting RNA from buccal smears. The project was conducted within
the geographical location of Leicester, Leicestershire and Rutland.
The recruitment for this study occupied a concentrated period of time due to the delay
in Research and Development and Ethics approval. The intended 24 month period of
recruitment was limited to 16 months, from March 2007 to July 2008. Physiological
monitoring took place in parallel to it. This put a significant time pressure on the
completion of the study as a maximum of eight infants at a time could have
physiological measurements made. Each recruitment and monitoring period lasted up
to 5 months. The delay in the commencement of this project due to the processes
associated with ethics (COREC) and Research and Development (R & D) approval
was a total of two years.