Understanding The Link Between Rem Sleep And Learning

Sleep is essential for the formation of long-term memories. Research suggests that sleep plays an important role in memory, both before and after a new learning situation.

Lack of adequate sleep affects mood, motivation, judgment, and our perception of events. Although there are some open questions about the specific role of sleep in forming and storing memories, the general consensus is that consolidated sleep throughout a whole night is optimal for learning and memory.

Different types of memories are formed in new learning situations. Scientists are exploring whether there is a relationship between the consolidation of different types of memories and the various stages of sleep.

The earliest sleep and memory research focused on declarative memory, which is the knowledge of fact-based information, or what we know. In one research study, individuals engaged in an intensive language course were observed to have an increase in rapid-eye-movement sleep, or REM sleep. This is a stage of sleep in which dreaming occurs most frequently. Scientists hypothesized that REM sleep played an essential role in the acquisition of learned material. Further studies have suggested that REM sleep seems to be involved in declarative memory processes if the information is complex and emotionally charged, but probably not if the information is simple and emotionally neutral. Researchers now hypothesize that slow-wave sleep (SWS), which is deep, restorative sleep, also plays a significant role in declarative memory by processing and consolidating newly acquired information. Studies of the connection between sleep and declarative memory have had mixed results, and this is an area of continued research.

Sleep plays a major role in the ability to learn new tasks that require motor coordination and performance.

Research has also focused on sleep and its role in procedural memory—the remembering how to do something (for example, riding a bicycle or playing the piano). REM sleep seems to plays a critical role in the consolidation of procedural memory. Other aspects of sleep also play a role: motor learning seems to depend on the amount of lighter stages of sleep, while certain types of visual learning seem to depend on the amount and timing of both deep, slow-wave sleep (SWS) and REM sleep.

The Impact of Sleep Deprivation on Learning and Performance

Another area that researchers study is the impact that a lack of adequate sleep has on learning and memory. When we are sleep deprived, our focus, attention, and vigilance drift, making it more difficult to receive information. Without adequate sleep and rest, over-worked neurons can no longer function to coordinate information properly, and we lose our ability to access previously learned information. In addition, our interpretation of events may be affected. We lose our ability to make sound decisions because we can no longer accurately assess the situation, plan accordingly, and choose the correct behavior. Judgment becomes impaired. Being chronically tired to the point of fatigue or exhaustion means that we are less likely to perform well. Neurons do not fire optimally, muscles are not rested, and the body’s organ systems are not synchronized. Lapses in focus from sleep deprivation can even result in accidents or injury. For more information about how sleep deprivation affects performance, see Sleep, Performance, and Public Safety. Low-quality sleep and sleep deprivation also negatively impact mood, which has consequences for learning. Alterations in mood affect our ability to acquire new information and subsequently to remember that information. Although chronic sleep deprivation affects different individuals in a variety of ways (and the effects are not entirely known), it is clear that a good night’s rest has a strong impact on learning and memory.

Although current research suggests that sleep is essential for proper memory function, there are unanswered questions, as in any area of active scientific inquiry. For example, certain medications will significantly, if not entirely, suppress REM sleep. However, patients taking these medications do not report any memory impairment. Similarly, injuries or disease causing lesions to the brainstem (and subsequently eliminating a person’s REM sleep) have not resulted in any obvious loss of the ability to form new memories. Exploration and debate continue.

REM sleep and slow-wave sleep play different roles in memory consolidation

REM sleep is characterised by rapid, low-voltage theta waves, muscle atonia and rapid eye/whisker movements. Slow-wave sleep is hallmarked by slow high-amplitude EEG oscillations.

Healthy sleep must include the appropriate sequence and proportion of NREM and REM phases, which play different roles in the memory consolidation-optimisation process. During a normal night of sleep, a person will alternate between periods of NREM and REM sleep. Each cycle is approximately 90 minutes long, containing a 20-30 minute bout of REM sleep. NREM sleep consists of sleep stages 1–4, and is where movement can be observed. A person can still move their body when they are in NREM sleep. If someone sleeping turns, tosses, or rolls over, this indicates that they are in NREM sleep. REM sleep is characterised by the lack of muscle activity. Physiological studies have shown that aside from the occasional twitch, a person actually becomes paralysed during REM sleep.

REM sleep is associated with the consolidation of nondeclarative (implicit) memories

REM sleep appears to play a critical role in the consolidation of nondeclarative memories. REM sleep is a stage of sleep in which dreaming occurs most frequently. Researchers have hypothesised that REM sleep plays an essential role in the acquisition of learned material. However, there is still no consensus on how sleep makes this process possible, and many researchers think that specific characteristics of brainwaves during different stages of sleep are associated with the formation of particular types of memory.

Animal studies have shown that REM sleep increases after completing a new course through a maze. Some researchers believe that the increase in REM sleep reflects an increased demand on the brain processes that are involved in learning a new task. Other researchers have suggested that any changes in the amount of REM sleep are due to the stress of the task itself, rather than a functional relationship to learning.

There is also evidence that different parts of the sleep cycle may be important for consolidation of different types of memories. For instance, slow-wave sleep may be important for consolidating declarative (fact-based) memory, while REM sleep may be important for procedural memory (how to do something).

Slow-wave, or non-REM (NREM) sleep, is associated with the consolidation of declarative (explicit) memories

Slow-wave sleep, or non-REM (NREM) sleep, is associated with the consolidation of declarative (explicit) memories. These are facts that need to be consciously remembered, such as dates for a history class.

Declarative memory has been shown to benefit from sleep, but not in the same way as procedural memory. Declarative memories benefit from the slow-waves NREM sleep. A study was conducted where the subjects learned word pairs, and the results showed that sleep not only prevents the decay of memory, but also actively fixates declarative memories. Two of the groups learned word pairs, then either slept or stayed awake, and were tested again. The other two groups did the same thing, except they also learned interference pairs right before being retested to try to disrupt the previously learned word pairs. The results showed that sleep was of some help in retaining the word pair associations, while against the interference pair, sleep helped significantly.

Lack of adequate sleep affects mood, motivation, judgment, and our perception of events

Sleep plays a major role in the ability to learn new tasks that require motor coordination and performance. Research has also focused on sleep and its role in procedural memory—the remembering "how" to do something. REM sleep seems to play a critical role in the consolidation of procedural memory. Other aspects of sleep also play a role: motor learning seems to depend on the amount of lighter stages of sleep, while certain types of visual learning seem to depend on the amount and timing of both deep, slow-wave sleep (SWS) and REM sleep.

The first memory step is encoding, in which you attend to an experience that is laid down in the brain. When a memory is first formed, however, it is unstable. This unstable memory trace may be quickly forgotten if it is not consolidated. Sleep appears to be critical to this consolidation process, allowing you to retrieve a memory at a later date. Although scientists are not precisely sure how sleep facilitates memory consolidation, a large body of evidence suggests that sleep is very important for later recall.

Sleep deprivation can be total (no sleep allowed), partial (either early or late sleep is deprived), or selective (specific stages of sleep are deprived)

Total sleep deprivation is when a person is not allowed to sleep at all. Partial sleep deprivation is when a person is allowed to sleep for a shorter duration than usual. Selective sleep deprivation is when a person is allowed to sleep for a normal duration, but specific stages of sleep are deprived.

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