Sunday, 24 August 2008

Memory research roundup - More Sleep

Following my last post, I received a comment from njtom as follows:

"Brain scans of humans and animals have indicated that bursts of information pass between the neocortex and the hippocampus during the first hours of sleep, known as slow wave sleep. It is during slow wave sleep that the brain remembers declarative or episodic memory – precise facts a person can access consciously."

If this is correct than how can the current medical advice to prevent Slow-wave sleep in infants be safe? Slow-wave sleep is when infants die of SIDS. So, doctors no longer allow infants to get slow-wave sleep. Is this safe?

This led me to read a couple of fascinating detailed research posts on the njtom's Tummy Sleep Central blog. The latest post covers Post-natal Slow Wave Sleep Inhibition and the SIDS "Back to Sleep" Campaign. Essentially the current advice to change an infant's sleeping position from tummy (prone) to back (supine) may be having a long term negative effect on their cognitive development while having a negligible effect on the reduction of SIDS deaths. Particularly resonant with my post is the following excerpt:

Since 1998 there have been three studies published which show that infants placed to sleep in the supine position lag in motor skills, social skills, and cognitive ability development when compared to infants who sleep in the prone position [35-37]. None of these three studies analyzed children older than 18 months of age and the authors of all three studies considered the lags at less than 18 months of age to be temporary and do not think that the supine sleep recommendations should be changed. Placing infants in the prone position while they are awake has been recommended to offset the motor skills delays associated with the supine sleep position [38] but positioning the infant prone while awake will not impact the amount of slow wave sleep [39-43].

These studies are covered in more detail in an earlier post and lead to further research that suggests supine sleep position increases apnea episodes and decreases sleep duration in infants. This nocturnal respiratory disturbance is associated with a decrease in learning in children who were otherwise healthy. Sleep fragmentation has an adverse impact on memory and learning (as indicated in my previous post), and that hypoxemia (a condition in which there is an inadequate supply of oxygen in the blood) has an adverse influence on nonverbal skills.

I don't know the answer to the question posed by njtom but it emphasises the importance of further research in how the quality of our sleep affects our cognitive development at all ages.


NJTOM said...

Great Blog! I'm sure I'll find the answer eventually. Another paper called "A reassessment of the SIDS Back to Sleep Campaign" also discusses this issue:

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