Good night, sweet dreams

A grotesque plaster statue is chasing you. You fall into a manhole and land on the sandy beaches of Antarctica. Suddenly gravity dissipates and you find yourself floating through the clouds below. Fortunately, you wake up and forget most, if not all, of the visually and emotionally bizarre adventure you’ve just endured — it was simply a dream.

Of the two major phases of sleep cycles, rapid eye movement sleep, from which principal dreams emerge, is the second stage of sleep that enhances memory and mood and triggers literal rapid eye movement. During a typical night of sleep, a person will cycle through alternating stages of non-REM and REM sleep in 90- to 120-minute intervals. 

“Emotional processing of waking memories occurs during REM sleep,” said Erika Yamazaki, Northwestern University neuroscience Ph.D. student. “We believe that it’s the processing of these memories that may be connected to dreaming.”  

REM sleep plays a significant role in boosting the immune system, consolidating memory and regulating mood. Thus, those unable to satisfy their body’s craving for REM sleep may feel fatigued and lethargic in the daytime.

“I run cross country and track, so sufficient sleep is really important for my speed, stamina and recovery between races,” junior Adit Kantak said. “Once I slept for five hours on a race day and I could feel that there was significantly less power in my legs than usual.”

REM sleep is commonly known as dreaming sleep, as dreams are stimulated by changes in activity levels of various regions of the brain during REM sleep. Magnetic resonance imaging studies have established that the prefrontal cortex — responsible for cognitive behavior and logical decision-making — is suppressed during this stage of sleep, temporarily deactivating rational thoughts. Similar studies have also shown stronger-than-normal activity in visual, motor and emotional regions of the brain during this stage of sleep.

“We don’t know why exactly we have dreams or what they mean but we suspect they help consolidate memories,” said Cheri Mah, M.D., M.S., sleep physician and Adjunct Lecturer at the Stanford Sleep Medicine Center. “There’s a lot of theories addressing this question, but the field of sleep is still very young and research is still ongoing.”

Scientists have long pondered the theory of dreams’ being epiphenomenal by-products of REM sleep, suggesting that dreams serve no significant purpose to the human body. One theoretical framework, however, postulates the importance of both sufficient REM sleep and dreaming for a good night’s sleep. UC Berkeley neuroscience and psychology professor Matthew Walker proposed this framework and referred to REM-sleep dreaming in his book, “Why We Sleep,” as “overnight therapy,” revealing two main functions of dreams: nurturing one’s mental health and inspiring creativity and problem-solving. 

During a 24-hour day, REM sleep is the only time in which a person’s brain is completely devoid of noradrenaline, an anxiety-triggering molecule. As a person enters the dreaming state, concentrations of noradrenaline begin to shut off while key emotion- and memory-related structures within the brain are reactivated. REM-sleep loss encourages higher levels of noradrenaline, thus increasing restlessness and anxiety. A common example of this phenomenon can be seen in human tendencies to stress and overthink at night and feel better in the morning.

“Sleeping is a pretty big stress reliever for me,” Kantak said. “Sometimes I have trouble falling asleep at night because of stress, but when I wake up in the morning I realize that everything is alright.”

 In addition to its mental-health benefits, brain activity during REM-sleep dreaming also extracts commonalities from knowledge obtained during the day by associating distant memories beyond the narrow scope of the conscious mind. One example Walker uses to illustrate this finding is language acquisition in babies: during their REM sleep, babies unconsciously extract the rules of grammar from daytime experiences, despite lacking explicit awareness of the rules. 

“Sometimes I think of really good solutions to life problems or conversations in my dreams,” sophomore Rhea Soni said. “I try to remember the solutions when I wake up but it feels like it’s just in the corner of my mind and I can’t reach it.”

Achieving sufficient REM sleep is crucial in optimizing creativity and consolidating memories from waking experiences. Mah describes the concept of memory consolidation as needing REM sleep to hit the “save” button on the material one has just studied; without that sleep, it would be harder to recall those memories in subsequent days.

Having a good night’s sleep is crucial to optimizing not only health but also performance during the day. To prioritize academics, social life or health, one must first prioritize sleep.

“It’s not impossible to balance your sleep, academics and social life simultaneously,” Mah said. “What you invest in your sleep is going to impact your performance in everything else — how you do in school, how you interact with friends and how you feel in general — so it’s important to put sleep first.”