The Development of Circadian Rhythms in Human Infants

This personal contact on the postnatal ward allowed the mother to meet the researcher
face to face before the home recruitment visit was made (should the family wish to
participate). This was thought to contribute to the high recruitment and retention rate.
The methods was chosen in preference to sending „anonymous‟ letters in mail shots
which may have had a much lower success rate as a recruitment strategy.
A follow up phone call was made to the family between 2 and 4 weeks later to elicit a
continued expression of interest. Families were then offered a home recruitment visit
to discuss in detail the project, the practicalities of participation and obtain written and
verbal consent.
Recordings were expected to take place on the infants between 6 and 16 weeks of age,
although in a few instances the monitoring took place just beyond these limits.
2.1.2 Recruitment visits in the home
If a mother consented, a recruitment visit was made following the confirmation of
expression of interest. The study protocol was discussed in more detail. The family
had the opportunity to see the equipment and kit that would be used for core body
temperature monitoring (data logger including the temperature probes), collection of
urine (for estimation of cortisol and melatonin), measurement of sleep (actiwatch) and
the buccal swabs (for collection and extraction of RNA). Examples of the
documentation used are in appendix 1. Participation was voluntary and a family
could withdraw at any time. GPs were informed of participation.
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