Sleep Deprivation May Impair Memory

Want a sharper memory? Get some sleep.

Sleep deprivation tends to hamper the brain's ability to make new memories, a new study shows.

The study, published online in Nature Neuroscience, comes from researchers at Harvard Medical School and Boston's Beth Israel Deaconess Medical Center.

In the study, Matthew Walker, PhD, and colleagues studied 28 healthy young adults aged 18-30 (average age: 22).

Walker's team split participants into two groups for the four-day study.

Starting on the first day, the researchers kept one group awake for 35 straight hours at the Beth Israel Deaconess Medical Center.

Those participants were allowed to use the Internet or email, take short walks, read, or play board games. But they weren't allowed to sleep — not even a quick nap.

Meanwhile, participants in the other group spent a normal night at home with no sleep restrictions.

Sleepy Brain Scans

At 6 p.m. the next day, all participants watched a slide show. They saw 150 slides of landscapes, objects, and people who weren't celebrities.

Meanwhile, participants got high-tech brain scans, using functional magnetic resonance imaging (fMRI).

Those brain scans showed that certain areas of the brain involved in memory were more active in participants who hadn't been deprived of sleep.

After the slide show, everyone went home to sleep, with no sleep restrictions. But the study wasn't over just yet.

Pop Quiz

The following evening, participants took a pop quiz on the slides they had seen 24 hours earlier.

They saw the same 150 slides, randomly mixed with 75 new slides.

Each slide was shown on a computer screen for a fraction of a second. Immediately after each image faded, participants had to indicate whether they'd seen it before.

Those who had been sleep deprived on the first night of the study performed worst — even though they'd had a night to catch up on their sleep.

Those results could be particularly important nowadays, as many people skimp on sleep.

Walker's team calls the findings "worrying considering society's increasing erosion of sleep time."

SOURCES: Yoo, S. Nature Neuroscience, Feb. 11, 2007; advance online publication. News release, Nature and the Nature Research Journals.