Actigraphic assessment of sleep-wake rhythm during the first 6 months of life.
OBJECTIVE
To examine the validity of the "Gaehwiler" actigraph (Gaehwiler Electronics, model Z80-32k V(1)) for the assessment of sleep-wake (S/W) rhythm and sleep structure in infants during the first 6 months of life using an algorithm developed in our laboratory to differentiate sleep and wake states.


METHODS
A continuous 72 h actigraphic recording was performed in 10 healthy infants at 1, 3 and 6 months of age. The actigraphic data were matched to direct observation of the infants' behavioural states. Using discriminant function analysis a scoring algorithm for automatic identification of S/W states from raw activity data was developed. The chi-square periodogram analysis was performed to estimate periodic components of S/W rhythm.


RESULTS
The overall agreement rates between the actigraphic and observer scoring for S/W were between 87 and 95% for the infants after the third month of life, while for the 1-month-old infants they never exceeded 72%. The actigraphic discrimination between active and quiet sleep was the best in 3-month-old infants. The circadian influence on S/W rhythm was already present by the end of the first month of life.


CONCLUSIONS
Using the "Gaehwiler" actigraph in our study, valid discrimination between sleep and wake states was obtained in infants during 3 and 6 months. The actigraph, however, did not provide valid active vs. quiet sleep state measures. The circadian rhythm of S/W was observed as early as during the first month of life.
Gnidovec
B
B
Institute of Clinical Neurophysiology, Division of Neurology, University Medical Centre, Zaloska 7, SI-1525 Ljubljana, Slovenia. barbara.gnidovec@mf.uni-lj.si
Neubauer
D
D
Zidar
J
J
D000465:Algorithms; D002138:Calibration; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D011589:Psychology, Experimental / Q000295:instrumentation*; D012016:Reference Values; D015203:Reproducibility of Results; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*