Poor Memory in Sleep Deprivation Linked to “Not Seeing”

Neuroscience_Neurology2.jpgMaybe, finally we know, why cramming all night in the weeks before the test, isn’t such a good strategy after all.

New research suggests that poor memory as a result of sleep deprivation is not so much as a result of not getting enough sleep that will allow the visual memory to consolidate in the brain; it has more to do with a fundamental defect of the sleep-deprived brain failing to “see” patterns it expects to.

In a recent study published by Drs. Michel Chee and Lisa Chuah from the Cognitive Neuroscience Laboratory, Duke–National University of Singapore, 30 volunteers underwent tests to compare their visual memory, while being presented with a sequence one to eight colored squares, before and after 24 hours of sleep deprivation. A significant drop in short term visual memory (STVM) was observed, which lead them to conclude that “deficits in visual processing and visual attention accompany and could account for loss of short-term memory capacity” in sleep deprivation. Subjects lacking sleep were simply not able to retain memories of objects presented to them over a certain threshold number.

These results could have profound implications for those who have jobs requiring regular periods of sleeplessness, like intensive care workers, HGV drivers, air traffic controllers or even army operatives. Crucial action relying on “seeing” correctly might be an integral part of some aspects of these jobs, a worsening of which is the precise problem when we are sleep deprived. In these situations, mistakes linked to seeing incorrectly can always be ascribed to sleep deprivation. While type-setting errors done by sleep-deprived press workers can be passed off as unintentional, mistakes in the previous job scenarios are potential major public safety hazards.

According to Dr. Chee, the reduction in the visual attention span in some was quite severe, even with one or two squares being presented. However, others appeared to be better off than others at visual tasks, despite the lack of sleep, which might make it feasible to create tests of suitability of candidates for jobs where sleep deprivation is unavoidable. This would probably involve the use of functional magnetic resonance brain scans, which allow us to observe and compare people’s brain’s working patterns in sleep deprived states.

Dr. Chee’s team is continuing to look at alteration in patterns of brain activity due to lack of sleep, which is part of a bigger picture of attention deficits, not restricted to vision only, but is the explanation behind poor general memory as well. Meanwhile it seems like a good idea to finish our exam preparation way before the last couple of weeks.


Michael Chee and Lisa Chuah. (2007) Functional neuroimaging and behavioral correlates of capacity decline in visual short-term memory after sleep deprivation. Proceedings of the National Academy of Sciences of the USA. 104 (22): 9487-9492.

Sudip Ghosh, MD

Sudip Ghosh, MD, is a surgeon at the University of Manchester, UK and a medical writer.
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