The Connection Between Endorphins, Sleep and Memory

Endorphins are a natural pain reliever that are released in the body when it experiences certain activities.  On one hand, they can block perception of pain while on the other hand, they can increase feelings of wellbeing.  They have been found to increase during times of physical activity, sex and laughter. Endorphins also play an important role in sleep and memory. In fact, they help regulate both processes for better quality of life.

In this post we will discuss how endorphins work with sleep and what the connection may be between endorphins and memory formation.

Read also: Exercise and Sleep

Endorphins and Sleep

There is a strong correlation between endorphin release in the brain, sleep patterns and memory. Endorphins are responsible for regulating our circadian rhythms which can impact both SWS (slow-wave sleep) as well as REM (rapid eye movement) sleep. A study on rats conducted by Maiken Nedergaard and her team, revealed that endorphins increase during SWS and decrease in the REM stage.

During slow-wave sleep (SWS), or deep sleep, the body repairs cells and tissue as we tend to experience less dreams.  It is not surprising then that a correlation between memory formation and increased levels of endorphin activity in this phase of sleep is evident in research.  Studies on rats have revealed that when endorphin levels are increased in the brain during SWS (deep sleep), memory formation is improved upon.

On the other hand, the REM (rapid eye movement) stage of sleep is associated with dreams and high level thinking processes like problem solving. Endorphin levels are decreased during this stage of sleep.  There has not been much research focusing on its impact on memory.

There does however seem to be a small connection between REM and memories which have formed at the beginning of the night before SWS takes over. These dreams can often include vivid sensory experiences- sounds, images and smells.

Read also: Sleep Cycles: How the Sleep Stages affect your Health

Memory Formation

The relationship between memory formation, sleep stages and endorphins is not only evident in research on rats.  One study conducted at the University of Bern by Andrea Antal et al., revealed that individuals who received an injection of naltrexone (a drug which blocks opioid receptors) showed a decrease in memory recall after sleep, when compared to individuals who received a placebo.

Another study by Antal et al., found that higher levels of endorphins in the brain were associated with better long-term and working memory performance during NREM (non-rapid eye movement). This result indicates a strong connection between memories formed at night vs those formed during the day.

The way in which our body responds to endorphins, whether it be through increased activity or decreased levels of memory formation can vary depending on a number of factors including age, gender and genetics. As science advances we are beginning to gain new insight into how these processes work- prompting us one step closer toward better sleep.

Endorphins and Memory

• Endorphins help regulate sleep patterns such as SWS (slow wave sleep) and REM (rapid eye movement). This can impact memory formation.
  
• Higher levels of endorphin activity in the brain are associated with better long term and working memory during non rapid eye movement; however, there is also a small connection between memories formed during rapid eye movement and those formed at the beginning of night before SWS.
  
• Endorphin levels in the brain are increased when there is physical activity, sex or laughter; this increases memory formation.
  
• Higher levels of endorphins in the brain correlate with better long term memory performance while lower levels correlate with decreased memory formation.
  
• Endorphins and their relationship to sleep and memory has been established through research on rats and humans.
  

The act of sleeping may feel like the absence of activity.  Our bodies are still, our eyes are closed, and we are not talking, interacting or otherwise being productive.  This could not be further from the truth.   Sleep is a critical part of every day, and our bodies and minds are performing so many necessary tasks while we sleep, including the formation of long-term memories.  The process of moving memories from short-term to long-term allows us to be successful in our academic and professional endeavors as well as to engage in social and emotional relationships at all stages of life. Within the important processes that occur within us during sleep, endorphins role affects both pain and pleasure which come together to improve our overall quality of life.