The problem

People who smoke a lot of marijuana often report they either don't dream or don't remember their dreams. That's because marijuana can diminish the quality of our REM — rapid eye movement — sleep. That's when our most vivid dreams occur. According to a sleep expert who recently published a review article, Dr. Rubin Naiman from the University of Arizona's Center for Integrative Medicine, we are in the midst of an epidemic of REM sleep deprivation. And he says it's not just marijuana that can affect our REM sleep.

'There are a number of factors that feed into this epidemic of diminished REM sleep. And one of them includes substances, which primarily are alcohol and cannabis ... So many of the most commonly used medications both prescription and over-the-counter medications can interfere with REM sleep. Examples include benzodiazepines or anti-anxiety agents antidepressants drugs that are known as anticholinergic, which are a range of medicines that affect a gastric function and also allergy. And finally sleep disorders themselves, primarily insomnia and sleep apnea, also contribute significantly diminishing REM sleep. - Dr. Rubin Naiman

How this affects us

The REM phase of our sleep is important for certain types of memory consolidation. Whereas slow wave sleep, or deep sleep, helps us remember facts. Dr. Robert Stickgold, who studies sleep and dreams, says that REM sleep helps us to process contextual and emotional memories. He says dreams are important too. "The dreams seem more to be involved in figuring out possible uses for the memory."

What this means for society

Millions of people around the world take these prescription medications and consume substances like alcohol and marijuana, it can be very easy to get used to not feeling great.

When we don't have good quality REM sleep, Dr. Stickgold says, "I think it leaves a lot of what we experience and what we learn during the day unprocessed. In some ways they're walking around as a shadow of themselves."