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Interrelationships between rapid eye and body movements during sleep: polysomnographic examinations of infants
Insights
In infants, body movements during rapid eye movement (REM) sleep decrease significantly with age. This suggests maturing brain-stem inhibitory mechanisms, with higher movement rates potentially indicating delayed development.
Area of Science:
- Neuroscience
- Developmental Biology
- Sleep Medicine
Background:
- Myoclonic twitches and rapid eye movements (REMs) are closely linked in animals.
- Limited research exists on the human infant relationship between body movements and REMs.
- Small body movements (BMs) in infants are considered analogous to animal twitches.
Purpose of the Study:
- To investigate the developmental trajectory of the relationship between body movements and REMs in human infants.
- To compare movement patterns in normal infants with those exhibiting signs of brain-stem immaturity.
Main Methods:
- Polysomnography was used to record sleep patterns in 33 normal infants (34-84 conceptional weeks).
- The percentage of body movements occurring during REM bursts was calculated.
- Sleep data from 5 infant patients with suspected brain-stem immaturity were analyzed.
Main Results:
- In normal infants, the percentage of body movements during REM bursts decreased sharply during early infancy, approaching zero.
- Infants with suspected brain-stem immaturity showed higher percentages of body movements during REM bursts.
- A contrast was observed between human infants and animals regarding body movement association with REMs.
Conclusions:
- Human infants exhibit fewer body movements during REM sleep compared to animals.
- Maturation of brain-stem inhibitory mechanisms during REM sleep likely causes the decrease in body movements.
- Elevated body movement percentages in REM sleep may indicate delayed brain-stem maturation in infants.
Abstract:
Myoclonic twitching and rapid eye movements (REMs) are believed to occur in close association in animals; but, there have been few studies on their interrelations in humans. Polysomnograms were made from 33 normal infants of 34-84 conceptional weeks of age in order to observe the developmental aspect of the relation between twitching and REMs. We examined the small body movements (BMs), which appeared to be equivalent to twitches in animals and calculated the percentage of BMs that occurred together with the REM bursts in comparison to the total number that occurred during active REM sleep (% BMs in REM bursts). Polysomnograms were also obtained from 5 infant patients whose pathophysiologies were considered to be due to brain-stem immaturity. Whereas the values showed abrupt decreases during early infancy, nearly reaching 0, for the normal infants, they were high in some of the patients' records. These results suggest that few BMs occur during REMs in humans as opposed to animals. The maturation of inhibitory mechanisms, which are located in the brain-stem and act during REMs, may account for the rapid decrease of % BMs in REM bursts during early infancy. Increases of this index may reflect delayed brain-stem maturation.