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Published on: October 2, 2019
Effect of infant sleeping position on sleep spindles
Rosemary S C Horne1, Chamali Egodagamage, Susan M Cranage
1Department of Paediatrics and Ritchie Centre for Baby Health Research, Monash University, 246 Clayton Road, Clayton, Victoria, Australia 3168. rosemary.horne@med.monash.edu.au
Insights
Infant sleep position affects sleep spindle characteristics. Prone sleeping in younger infants (2-3 months) shows reduced sleep spindle density compared to supine, but this difference diminishes with age. Spindle characteristics did not correlate with arousal thresholds.
Area of Science:
- Neuroscience
- Sleep Medicine
- Developmental Pediatrics
Background:
- Sleep spindles are crucial for sleep maintenance and arousal modulation.
- Previous research indicated prone sleeping impairs arousal in 2-3 month olds, but not 5-6 month olds.
- The impact of sleeping position and age on sleep spindle characteristics remains unclear.
Purpose of the Study:
- To investigate how sleeping position (prone vs. supine) and postnatal age influence sleep spindle duration and density in infants.
- To determine if sleep spindle characteristics correlate with infant arousal thresholds.
Main Methods:
- Polysomnography was used to study 21 healthy term infants at 2-3 months and 16 at 5-6 months.
- Infants slept in both prone and supine positions during daytime naps at each age.
- Sleep spindle duration, density, and proportion of non-rapid eye movement (NREM) sleep with spindles were analyzed.
Main Results:
- At 2-3 months, supine sleeping showed significantly higher spindle density and a greater proportion of NREM sleep with spindles compared to prone sleeping.
- At 5-6 months, spindle duration was longer in the supine position.
- Prone sleeping exhibited increased spindle density at 5-6 months compared to 2-3 months.
- No correlation was found between arousal threshold and sleep spindle density or percentage of NREM sleep with spindles.
Conclusions:
- Sleeping position impacts sleep spindle characteristics in infants, particularly at younger ages.
- While sleep spindle density and duration change with age and position, they may not serve as reliable markers for depressed arousal responses in infants.
- Developmental changes in sleep regulation influence the relationship between sleep architecture and arousal sensitivity.
Abstract:
Sleep spindles play an active role in inducing and maintaining sleep and may affect arousal by blocking the transmission of external stimuli through the thalamus to the cortex. Previously we have demonstrated that sleeping in the prone position impairs arousal in infants at 2-3 months of age, but not at 5-6 months. We aimed to examine if sleeping position and postnatal age affected duration and/or density of sleep spindles. Twenty-one healthy term infants were studied using daytime polysomnography at 2-3 months and 16 were again studied at 5-6 months. Infants slept both prone and supine at each study. The mean duration of non-rapid eye movement (NREM) sleep was not different between the two studies in either position. At 2-3 months both spindle density (P < 0.001) and proportion of NREM sleep (P < 0.025) with spindles were significantly greater in the supine than in the prone position. At 5-6 months spindle duration was longer in the supine than in the prone position (P < 0.03). Spindle density in the supine position was not different between the two studies, however, when infants slept prone, it was significantly increased at 5-6 months compared with 2-3 months (P < 0.001). Arousal threshold was not correlated with either spindle density or percentage of NREM sleep with spindles in either position at either study. In this study spindle density and the percentage time spent with spindles were not well correlated with infant arousability, and hence may not be able to be used as markers of depressed arousal responses in infants.
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