Abstract
To evaluate the influence of prematurity and postnatal age on the relationship between
motor activity (MA) and sleep states, forty clinically and neurologically normal infants
were recorded polygraphically and grouped according to their gestational (GA, prematures:
< 36 weeks, full-term: 37 - 41 weeks) and conceptional (CA, 37 - 38 and 39 - 41 weeks)
ages. Sleep states (active: AS, and quiet: QS) were defined by the concordance of
EEG and rapid eye movement criteria. Movements of both upper (UL) and lower (LL) limbs
were independently recorded.
In all groups the amount of MA in both UL and LL clearly predominated in AS compared
with QS (p < 0.02). Contrariwise, both the longest period without movement and the
no-movement 20-sec epochs were significantly higher in QS than in AS (p < 0.005).
In AS, age-related modifications and modulation of MA amount throughout the state
were similar for PRT and FT groups: a) in both groups a significant decrease of MA
with advancing CAwas observed (p < 0.05); b) MA throughout the state was randomly
distributed regardless of CA. In QS, however, PRT were distinguishable from FT by
the absence of: a) a significant decrease of MA amount with advancing CA, together
with a reduced increase of both the longest period without movements and the no-movement
20-sec epochs; b) prevalence of MA in LL compared with UL; c) modulation of the distribution
of MA throughout the state.
In conclusion, our results suggest that during QS, MA patterns of PRT differ from
those of FT neonates even when time from conception is equal for both.
Key words
Motor activity - Prematures - Full-term newborns - Sleep states - EEG
