Dream Deprivation: How Loss of REM Sleep Impacts Health and Learning

It has been more than 65 years since rapid eye movement (REM) sleep was first described in 1953 by one of the founders of sleep medicine, Nathaniel Kleitman, Ph.D., in his research on the mysteries of sleep. Decades later, we still have much to learn about the nature of this phase of sleep.

There is some concern that REM sleep deprivation may have important impacts on health. This may occur in the setting of insufficient sleep, the use of antidepressant medications, and with coexisting sleep disorders. How might the loss of dreaming sleep affect memory, learning, and mood?

Rapid eye movement (REM) sleep is one of the two major categories of sleep stages that naturally occur. It is so distinctive that the others are sometimes lumped together simply as non-REM sleep. What are the classic characteristics of REM sleep?

Modern sleep studies, such as a polysomnogram, measure brain wave activity with an EEG, muscle activity with an EMG, and eye movements with an EOG. By definition, REM sleep is noteworthy for the presence of an active brain and the paralysis of skeletal muscles. In fact, very few muscles of the body remain active during this phase of sleep. The muscles used in eye movements and the diaphragm (necessary for ongoing breathing) continue to function. This paralysis may prevent the enactment of dream content, as vivid dreams are another core feature of REM sleep. Without this paralysis, REM sleep behavior disorder may occur.

Research seems to support the notion that REM sleep has an important role in daytime function. It may contribute to learning and memory consolidation, but the research is not conclusive. Specifically, it may help someone to learn a new skill. An example of this procedural memory could be learning how to ride a bicycle. It differs from factual, or semantic memory, such as memorizing a list of vocabulary words.

Beyond its role in procedural memory, it is hypothesized that REM sleep may also have a role in problem-solving. Unique connections may be made within the brain, allowing novel discoveries to be made. 

The vivid dreams of REM sleep are often experienced like a movie unfolding in which the sleeping person is an actor in the story. When the content of the dream is disturbing, nightmares may result. Mood disorders like anxiety and depression and post-traumatic stress disorder (PTSD) may impact the experience of dreams.

If REM sleep serves a vital function, the loss of it may be worrisome.

Much has been made of the impacts of sleep deprivation on health. When insufficient sleep is obtained to meet sleep needs, there are real consequences to health and well-being. Sleep deprivation not only causes sleepiness and the inherent risks, but it seems to wreak havoc on metabolism, pain, and cardiovascular health. What if the same is true for REM sleep loss? How might someone become dream deprived?

First, let’s consider the usual structure of sleep. REM sleep normally occurs at regular intervals through the sleep period. Every 90 to 120 minutes, REM sleep may occur. These periods may last 5 to 30 minutes and typically become longer towards morning so that most REM sleep is experienced in the last one-third of the night. It is common to interrupt the last period of REM sleep upon awakening.

There are certain situations when REM sleep may be either reduced or absent from sleep. Sleep deprivation due to inadequate total hours of sleep may lead to an absolute reduction in the time spent in REM, but the percentage of the night in REM sleep may actually increase. This occurs because lighter sleep may be eliminated with sleep consolidation.

Substance use has a profound impact on REM sleep. The following are known to suppress REM sleep:

• Caffeine
• Alcohol
• Marijuana
• Opioid (narcotic) pain medications
• Benzodiazepine medications
• Antidepressant medications
• Lithium

Beyond these impacts, sleep disorders, especially obstructive sleep apnea and narcolepsy, may lead to fragmented periods of REM sleep. The muscle relaxation of REM may cause airway muscles to collapse and trigger breathing disturbances seen in sleep apnea. This may curtail the persistence of REM. When sleep apnea is effectively treated with continuous positive airway pressure (CPAP) therapy, this may lead to a profound rebound of REM sleep.

One might guess that the widespread use of alcohol and antidepressants, the high prevalence of sleep apnea, or the impacts on sleep deprivation may have profound detrimental impacts on societal health. Unfortunately, research has not proven this out.

If there is a vital process achieved by REM sleep, why is there is no discernible effect when deprivation occurs continuously for decades with chronic antidepressant use? Even subjects with permanent damage to the REM-generating part of the brain can have normal memory and no perceptible loss of function. The biologic need that is satisfied by REM sleep remains unknown.

There is clearly increased metabolic activity in the brain during REM sleep, but to what end? Are systems simply being fired to ensure they are working? Does this prime the brain to more quickly return to consciousness towards morning? Does the chemical shift that occurs (specifically the cessation of the activity of histamine, norepinephrine, and serotonin) allow a reset of metabolic pathways and optimized sensitivity to the neurotransmitters? Or is there something more to this mysterious state of consciousness? It is interesting to speculate and exciting to consider that it may someday be learned.

If you are concerned about the impacts of REM sleep deprivation, reach out to your local board-certified sleep physician. Education about your potential risks and, if needed, a diagnostic sleep study may be helpful. More research is needed to elucidate these potential impacts, but optimizing your sleep will always help you to feel your best.