Social life linked to sleep, memory

An experiment on fruit flies has proved that socialising has a tremendous impact on our brains.

An experiment on fruit flies has proved that a hectic social life makes socialites take longer naps. This finding could prove important in helping to understand why we sleep, and what effect socialising has on our brain circuitry.

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The impact of sleep on our memories is an area of great interest for neuroscientists.

It has been shown previously that sleeping on a newly learned task can improve performance, and that disrupting sleep can affect learning.

So sleep is thought to be important in the process by which the brain organises and consolidates memories. "It's not cool to consider sleeping as just a waste of time," says Indrani Ganguly-Fitzgerald of the Neurosciences Institute in San Deigo, California.

To investigate how increased social experiences might affect sleep and memory, Ganguly-Fitzgerald and colleagues turned to fruitflies (Drosophila melanogaster).

The researchers took flies immediately after birth and put them into groups: some went into a social environment with at least 30 other flies, others went into isolation. They stayed there for 3 to 4 days before being tested.

All this suggests that afternoon naps may be important for consolidation of memories, whereas night-time sleep may have a different function for flies.

"I'm a strong believer in flies as models to study sleep, which I admit has been quite difficult to convince the sleep community in general," says Chiara Cirelli of the University of Wisconsin, Madison, who was involved in the 2000 paper showing that flies do sleep.

This latest paper, she agrees, shows an interesting link between socialising, sleep and memory.

"It is another demonstration that flies can be extremely powerful models."