Twenty-four-hour and Ultradian Rhythmicities in Healthy Full-Term Neonates: Exogenous and Endogenous Influences

Abstract

Eleven healthy, full-term babies were studied on the second day after birth and again 4 weeks later. The babies lived on a 24-h light/dark cycle (light from 0700-1900) and were bottle-fed every 4 h. Systolic blood pressure, heart rate, skin (abdomen) and rectal temperatures were measured at 10-min intervals for 24 h on each occasion of study. The behavioural state of the baby was measured at the same time, and this information was used to purify the raw data (i.e., to separate it into the endogenous, clock-driven and exogenous, lifestyle-driven components). Raw and purified data were assessed for 24-h and ultradian (12-, 8-, 6-, 4-, 3-, 2-h) periodicities by cosinor analysis. We confirm the development of 24-h rhythmicity in skin and rectal temperatures between day 2 and week 4; at the same time, ultradian rhythms (4-h) developed in all variables. For heart rate and systolic blood pressure the development of a 4-h ultradian rhythm was in phase with the behavioural changes produced by feeding; by contrast, for the temperatures, these weak exogenous components were accompanied by a stronger 4-h component, that was out of phase with feeding. Masking effects due to sleep and activity changed in size between day 2 and week 4. Also, those positive masks produced by waking activities were more marked in the light, whereas the negative masks produced by sleep were more marked in the dark. Some implications of these results for the development of rhythmicity in infants, particularly whether due to lifestyle or the development of internal processes, are discussed.

Circadian rhythms and sleep in children with autism

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The human newborn’s umwelt: Unexplored pathways and perspectives

“…Nevertheless, reports on sensory perception rarely describe newborns' sensory environment in detail beyond the particular stimulations studied, although it can vary immensely between hospitals. Many studies underline a short-term impact of external sensory stimulations on physiological and behavioral measures of newborns (Bertelle, Mabin, Adrien, & Sizun, 2005;Goubet et al, 2003; Jaldo-Alba, Muñóz-Hoyos, Molina-Carballo, Molina-Font, & Acuña-Castroviejo, 1993;Philbin, 2000;Rivkees, Mayes, Jacobs, & Gross, 2004;Weinert, Sitka, Minors, Menna-Barreto, & Waterhouse, 1997). For instance, premature newborns' sleep durations and weight gains are influenced by environmental conditions such as levels of noise and light (Bertelle et al, 2005;Mann, Haddow, Stokes, Goodley, & Rutter, 1986).…”