Decreased Total Sleep Time Associated With Increased REM Sleep During Subsequent Naps

The study, authored by Jennifer Kanady, of the University of California at San Diego, focused on 24 healthy subjects, who wore an actigraph for seven nights while adhering to a regular sleep-wake schedule followed by a 90-minute, polysomnographically-recorded nap. The influence of two-night and seven-night averages of total sleep time immediately prior to the nap on nap architecture was examined.

According to the results, less prior nightly total sleep time increased the percentage of REM sleep during the nap. Average total sleep time did not affect any other architecture variable of the nap. Bed and wake time appear to influence REM sleep percentage only in the short-term.

"The findings of our study indicate that minute differences in 'normal' sleep duration influence the percentage of REM sleep obtained in a subsequent afternoon nap," said Kanady. "Specifically, 10 minutes less sleep per night led to a 1.3 percent increase in nap REM percentage. These results may have important implications for studies examining sleep-dependent memory consolidation, particularly those studies that highlight the importance of REM sleep."

It is recommended that adults get between seven and eight hours of nightly sleep.