DEEP SLEEP DOESN'T HELP MEMORY.

Byline: Dominic Berbeo Staff Writer

NORTH HILLS - Students who go to bed early to be ready for a big test the next day might be missing the mark, according to a study to be released today by a San Fernando Valley researcher that finds a good night's sleep does not increase memory.

The study questions the long-held notion that deep snoozing - known as REM, or rapid eye movement, sleep - helps memory retention.

``There are many kinds of brain activity that can affect the memory, but there is no conclusive evidence to show that REM sleep helps memory consolidation,'' said the study's author, Jerome M. Siegel, researcher at the Center for Sleep Research, Department of Veterans Affairs in North Hills, and the Department of Psychiatry and Brain Research Institute at the University of California, Los Angeles.

``However, I do not mean to say that sleep is not important in helping you learn things,'' he said. ``The way disturbed sleep disturbs one's learning is by lessening concentration, not one's memory.''

The study evaluates literature and scientific studies over the past 50 years, and is scheduled to be released in today's version of Science Magazine.

The findings drew mixed reactions from students at a West Valley mall.

``I wish I had the time to find out if more sleep would help,'' said Jason Borges, 19, of Canoga Park, who said all-night studying is normal for him and a few friends. ``But I work and go to school, so I never get to sleep much.''

Amy Tellez, 20, said she always tries to avoid all-night cram sessions before tests.

``I don't know if it helps your memory, but if you're sleepy, there's no way you're going to do well,'' she said.

REM sleep is a deep sleep during which an individual's eyes dart rapidly under closed eyelids and the body is almost completely paralyzed except for the heart, diaphragm, eye muscles and internal organs.

Humans on average get about two hours of REM sleep per eight hours of sleep, usually just after falling asleep, Siegel found.

Other mammals with high brain and memory capacity, such as dolphins and giraffes, get little to no REM sleep, he found.

Siegel said the widespread notion that REM sleep allows the brain to convert short-term memory to long-term memory - known as ``memory consolidation'' - has been based largely on assumption, and is not true.

``A mix of positive and negative results in human studies has led many sleep-learning researchers to suggest that REM sleep may not be important for certain kinds of memory, such as what has been termed `explicit' or `declarative' memory,'' the study said.

``REM sleep would thus be excluded from having any substantial role in much of what is considered to be unique in human intellectual capacity.''

Siegel further asserts that studied subjects who took drugs that induced REM sleep deprivation did not necessarily have a lessened memory capacity.

The findings present a thought-provoking break from previously held beliefs on the affects of REM sleep, said Merril Mitler of the Scripps Research Institute Department of Neuropharmacology Laboratory for Sleep, Fatigue and Safety in La Jolla.

``It's a critical article that should be well-received,'' he said. ``However, I expect there will be debate.''

Mitler, co-author of the book ``101 Questions About Sleep and Dreams,'' said REM sleep has also been widely believed to benefit the brain in other ways. Benefits range from wish fulfillment to providing necessary stimulation to the entire nervous system during development.

But, he said, scientific proof is difficult.

``This is not always such a clear-cut science,'' he said. ``Conclusions are not always black and white.''

Siegel said identifying factors that negatively affect memory capacity was much simpler.

For example, it is generally accepted that alcohol use shrinks a certain part of the brain, creating a vitamin B deficiency and reducing memory, a process known as the Kosakoff Syndrome.