When we dream, we're in our deepest sleep

"Is it possible you don't dream at night?," asked Tabitha Grose, 10, of Mundelein, a soon-to-be fifth-grader at West Oak Middle School in Mundelein.

When you sleep, you dream. Dreams are pictures in your mind, feelings or ideas you experience while sleeping. Oneirology is the scientific study of dreams.

"It's very unlikely that a child doesn't dream at all," said Dr. Leila Kheirandish Gozal, a specialist in pediatric sleep medicine at the University of Chicago Medical Center.

"Dreams are part of our sleep. Every night when we sleep, our sleep goes through several stages from shallow sleep all the way to deep sleep. One of the important sleep stages is called rapid eye movement or REM sleep," Dr. Gozal said.

REM is when the body is in its most relaxed state, but the brain is in a very active state, similar to being awake. This is the stage when dreams occur. During REM, the body experiences atonia - it almost can't move, making it less likely to act out the images conjured up in dreams. Since the brain is in an active stage, it can wake the body if there's danger.

"A healthy child has almost four or five episodes of REM sleep every night. We spend almost two hours each night dreaming, but most dreams last only five to 20 minutes," Dr. Gozal said.

REM was discovered in the 1950s by a University of Chicago medical student. A dream is more likely to be remembered if a person is wakened during REM. "Most people usually remember their last dream," Dr. Gozal said. "Remembering a dream is subjective."

REM has a key role in body and brain functions. "It is very important to have a good night's sleep. REM helps consolidate memory. During the day we actively learn and gather information. When we sleep, the information is organized and arranged by our brain to help us recall the information later," Dr. Gozal said.

Other sleep stages are also important to overall health.

"Sleep is very important for the brain development in children," Dr. Gozal said. "Lack of sleep or a poor sleep quality can result in lower school performance."

Doctors recommend that children sleep between 9 and 11 hours every night.