Broken sleep harms memory

Wednesday, 27 July 2011, 16:39 IST
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London: Experiencing fragmented sleep? It's high time that you consulted a doctor, for a study says it affects the ability to build memories and could raise the risk of developing dementia in later life. Sleep continuity is one of the main factors affected in various pathological conditions that impact memory including Alzheimer's disease and other age-related cognitive deficits, said Dr Luis de Lecea, who led a team at Stanford University which carried out the study. Researchers have, in fact, based their findings on an analysis of laboratory rodents, the findings of which are published in the latest edition of the Proceedings of the National Academy of Science journal. In their study, the researchers found disrupting sleep made it harder for the animals to recognise familiar objects. This study looked at sleep that was fragmented, but not shorter or less intense than normal for the mice. It used a technique called optogenetics, where specific cells are genetically engineered so they can be controlled by light. The researchers targeted a type of brain cell that plays a key role in switching between the states of being asleep and being awake. They then sent light pulses directly into the brains of mice while they slept. This meant they could disrupt their sleep without affecting total sleep time or the quality or composition of sleep. The animals were then placed in a box with two objects, one of which they had encountered before. Mice would naturally spend more time examining the newer object, and those who had been allowed uninterrupted sleep did just that. But those whose sleep had been disrupted were equally interested in both objects, suggesting their memories had been affected. Broken sleep also affects people addicted to alcohol, and those with sleep apnoea, a condition in which the throat repeatedly narrows or closes during sleep, restricting oxygen and causing the patient to wake up.
Source: PTI
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