CanWest News Service
Published: Monday, July 31, 2006

WEST PALM BEACH, Fla. - Sleep benefits an individual's ability to recall recently learned memories, say researchers from Brigham and Women's Hospital, Harvard Medical School and the University of Pennsylvania.

This finding is particularly important for individuals with mentally demanding lifestyles, such as doctors, medical residents and college students, who often do not get adequate amounts of sleep. The study appears in Current Biology.

Sixty participants (33 women and 27 men) between the ages of 18 and 39, who did not use prescription or illicit drugs and did not have known sleep disorders or abnormal sleep patterns, were chosen for the study. Forty-eight individuals were assigned to one of four groups: sleep before testing, wake before testing, sleep before testing with interference, or wake before testing with interference.

All groups learned 20 paired words, which had no obvious semantic relationships. Twelve hours later, everyone was tested for recall by completing a cued-recall task; however, individuals within the interference groups learned a second list of 20 word pairs before testing. Participants were prevented from rehearsing the new words after learning the list.

The researchers found that in the non-interference groups mean recall was slightly higher in the sleep group compared with the wake group; however, participants in the interference condition who were able to sleep did significantly better on the recall task.

"The results show that the sleep benefit for memory persists across the subsequent waking day, even when challenged by new information," said Dr. Jeffrey Ellenbogen, an associate neurologist at Brigham and Women's Hospital.
© The Edmonton Journal 2006