Disrupted sleep could have role in Alzheimer's

Published on Monday 25 July 2011 15:13

BROKEN sleep may partly explain the memory loss associated with ageing, Alzheimer's and alcoholism, a study suggests.

Scientists used a technique that controls brain cells with light to demonstrate the link between sleep and memory in mice.

They showed that sleep continuity, rather than the quality or total amount of sleep, was important for memory.

Working at the cellular level, fragmenting sleep made it harder for mice to remember familiar objects.

The findings may have implications for the understanding of memory impairment related to ageing and a range of medical conditions, say the researchers in the journal Proceedings of the National Academy of Sciences.

The US scientists, led by Dr Luis de Lecea, from the University of Stanford in California, wrote: "Sleep continuity is one of the main factors affected in various pathological conditions that impact memory, including Alzheimer's and other age-related cognitive deficits."

Sleep has long been thought of as important for memory but unravelling the precise ways the two are linked is difficult. Conventional sleep deprivation leads to muddled effects of stress, reduced total sleep time, and changes to the intensity or quality of sleep.

The mice had their memory tested by placing them in a box containing two objects, one of which they had encountered before.

Rodents are naturally curious and will always spend time investigating an object seen as "new".

In the test, mice allowed uninterrupted sleep spent longer exploring the unfamiliar object.

But those whose sleep had been disrupted were equally interested in both objects, indicated that their memory was affected.