Monday, August 15, 2011
Fragmented Sleep and Memory
Researchers published a study at the end of July in the Proceedings of the National Academy of Sciences about the effect of sleep fragmentation and memory in mice. Studies have shown memory problems can occur when sleep is frequently disrupted. However, scientists are not sure if the memory problems are due to shorter total sleep time, poor sleep quality, reduction in a particular sleep stage (e.g. dream or REM sleep), or from the annoyance of being repetitively awaken.
In this study, the researchers used a new technique to isolate the effects of sleep fragmentation from overall sleep quality. The mice's brains were prodded awake every 60 seconds for one night, and this resulted in measurable memory problems. The interesting part is that the frequent awakenings did not reduce REM or deep sleep percentages, the total amount of sleep, or appear to cause the mice any stress.
The researchers suggest that new skills and information are committed to memory during sleep when our brains replay recently learned actions or sequences. The frequent awakenings interrupt that process such that the memories can be lost or compromised before they are stored.