Memories are vital to us. We need them to learn, to love, to grow, to recognize, and to work. Memory consolidation, when the brain saves important memories and discards unnecessary details, takes place during REM (rapid-eye movement) and NREM (non-rapid-eye movement) stages of sleep.
As every student knows, lack of sleep affects this memory consolidation process. What is more surprising is that excessive sleep can also cause memory problems. It turns out that getting too much sleep is no more helpful than getting too little.
If you think your lack of sleep is impairing your ability to remember, call the better sleep specialists at Silent Night Therapy for an appointment. You can reach us at 631-983-2463 or schedule your complimentary consultation online.
Memory, Sleep, and Learning
Resting and sleeping are when the brain processes new information. Anyone who has watched toddlers play hard and then sleep hard has seen this information processing in action. For adults, the information processing is slower and broken into distinct sleep phases.
The first two are called “light NREM” sleep, and the third is “deep” or “slow-wave NREM” sleep. The “slow-wave” refers to the patterns the brain waves make on an EEG machine. These stages prepare the brain to process new information the next day. If the brain was a computer hard drive, these phases would be like formatting the brain to accept new programming.
During the various NREM phases, the brain sorts through memories, saves the important ones, and discards unnecessary or duplicate details. This process may be why we do not have memories of every single drive to and from the office every single day. Our brain deletes the repetitive details and saves only the most important memories.
Sleep deprivation during NREM sleep affects the ability to learn the next day. Not sleeping, or not getting enough NREM sleep, can reduce learning capacity by as much as 40 percent. So not only will the ability to recall things be impaired, the ability to form new memories is greatly reduced.
Learning to Dream and Dreaming to Remember
Dreams occur primarily in REM (“rapid eye movement”) sleep. This refers to the twitching movements the eyeballs make when a person is dreaming. Emotional memories are also filtered through the brain during REM sleep, and it is believed this helps cope with difficult or stressful experiences.
A portion of the brain called the thalamus is responsible for most of the sensory activity in the brain. During NREM sleep, the thalamus is not active, but during REM sleep, the thalamus transmits sensory information, such as sounds, sights, and emotions to the dreaming cortex. These sensory cues are woven into the memories and become part of the dreams.
Because the sorting process is not linear, and the two portions of the brain, the cortex and the thalamus, are not completely in sync during dreaming as they are during waking hours, the sensory cues and memories become interrelated in very unusual ways, leading to the surrealism of dreams.
Sleep Deprivation and Memory Impairment
Nearly everyone has experienced sleep deprivation at some time in their lives. Students have struggled through all-nighters during finals week, and new parents work all day after sitting up with cranky babies all night. What are some of the effects of chronic sleep deprivation?
The most common symptom, unfortunately, is difficulty remembering things. Sleep and the stages of NREM and REM sleep prepare the brain for remembering and learning, so a lack of sleep means the brain does not have enough time to create paths for new information. Every college student recalls a time when they stayed up all night cramming for a final and then were unable to remember anything when they got to class.
Because one of the things NREM sleep does is discard unneeded information, the brain of a sleep-deprived person is cluttered with extra information blocking access to needed memories. Using the computer hard drive analogy again, the brain of a sleep-deprived person needs to be defragmented so it can run faster.
How Much Sleep Is Enough? How Much is Too Much?
Younger brains that run faster and process more information need more sleep, and as the parents of infants and toddlers know, they often take it wherever they are. Newborns and infants need at least 15-17 hours of sleep a day as their growing brains fill with new information.
School-age children need at least ten hours a day, and unfortunately, most of them never get that much. Parents and teachers of cranky, sleep-deprived teens know that the one thing every high school student really needs is more sleep, especially when they must do well in class.
Studies indicate that sleep quality tends to decrease with age, particularly in the “slow-wave” NREM sleep. As people age, the portion of the prefrontal cortex responsible for this type of sleep deteriorates, and as a result, they experience less of this memory-processing sleep. This may be why older people have difficulty processing memories later in life.
Too much sleep, more than the recommended amount of eight to ten hours per day, is also not beneficial, as it is often linked to other disorders. Insomnia, sleep apnea, depression, even diabetes, and heart disease can all contribute to excessive sleep. Too much time in NREM sleep can lead to difficulty accessing memories, or cause problems with learning the following day.
Quality Sleep and Quality Memory
By getting the recommended amount of sleep nightly, and ensuring your brain is getting the rest and reformatting that it needs, you will be developing the pathways necessary for better learning the following day.
You will also be clearing your head of all the unnecessary details that clutter up your brain and make it hard to remember the important things. Quality sleep ensures that you don’t remember everything about every day, only the things that really matter. If you feel as though you’re wandering in a haze of half-remembered bits and pieces from last week, you probably didn’t get a good night’s sleep.
We Can Help
If you feel sleep deprived or if your sleep does not seem as restful as it should, you might have sleep apnea or another sleep disturbance. Contact Silent Night Therapy at 631-983-2463 or take our online evaluation to see if you need to have your sleeping habits reviewed. Don’t forget! Your sleep is important.