REM and Memory

According to a report published in the February first issue of the journal Sleep, a short period of non-REM sleep during a daytime nap improves memory performance. However, this seems to be the case only when the person is quizzed on subjects he or she knows well.

Matthew A. Tucker, PhD, of the Center for Sleep and Cognition and the department of psychiatry at Harvard Medical School, and author of this study, says "These results suggest that there is a threshold acquisition level that has to be obtained for sleep to optimally process the memory." In conclusion, Dr. Tucker added: "The importance of this finding is that sleep may not indiscriminately process all information we acquire during wakefulness, only the information we learn well."

According to a second study, also published in the February first edition on Sleep, REM sleep deprivation reduces cell proliferation in the part of the forebrain that contributes to long-term memory. This second study was authored by Dennis McGinty, PhD, of the V.A. Greater Los Angeles Healthcare System.

The American Academy of Sleep Medicine (AASM) offers these tips for getting a good night's sleep.

• Follow a consistent bedtime routine.
• Establish a relaxing setting at bedtime.
• Get a full night's sleep every night.
• Avoid foods or drinks that contain caffeine, as well as any medicine that has a stimulant, prior to bedtime.
• Do not bring your worries to bed with you.
• Do not go to bed hungry, but don't eat a big meal before bedtime either.
• Avoid any rigorous exercise within six hours of your bedtime.
• Make your bedroom quiet, dark and a little bit cool.
• Get up at the same time every morning.

What is REM sleep?

There are five stages of sleep ranging from stage one, a very light sleep, deeper and deeper into stage four, a deep, restorative sleep. Stages one to four are classified as NREM (non-REM sleep.) The final phase is stage five, or REM (Rapid Eye Movement) sleep. If you were to watch someone during this phase of sleep, you could see the movement of the eyes beneath the closed eyelids. It's during this REM sleep that dreams occur. So do nightmares.

Dreams occur during REM sleep. We typically have 3 to 5 periods of REM sleep per night. They occur at intervals of 1-2 hours and are quite variable in length. An episode of REM sleep may last 5 minutes or over an hour.
REM sleep is characterized by a number of other features including rapid, low-voltage brain waves detectable on the electroencephalographic (EEG) recording, irregular breathing and heart rate and involuntary muscle jerks.