A woman sleeping in bed

From Zzzs to memories: How sleep habits shape cognitive function

There are several factors that can influence an individual’s memory—and sleep habits are crucial. Beyond influencing our ability to fight disease and develop immunity, proper sleep is also essential for improving our overall brain performance. 

Photo of Masashi Tabuchi
Masashi Tabuchi 

In recognition of National Memory Day (March 21), The Daily spoke with Masashi Tabuchi, an assistant professor in the Department of Neurosciences at Case Western Reserve University, for a closer look at how sleep shapes cognitive function.

Learn more about sleep’s impact on human health in Tabuchi’s latest research. 

Read on to learn more. 

Answers have been edited for clarity and length. 

1. Sleep plays a critical role in memory consolidation through several physiological processes, including memory organization, hormonal regulation and memory replay. 

Sleep has been characterized as a brain state that optimizes memory consolidation, with different sleep stages playing specific roles. Slow-wave sleep (SWS) is particularly important for memory consolidation, during which memories undergo a system consolidation process. This involves the reactivation of recently encoded neural memory representations, which are then transformed for integration into long-term memory. Subsequent rapid eye movement (REM) sleep may further stabilize these transformed memories.

2. Sleep has a significant impact on the retention of information learned during the day.

Research suggests that sleep, particularly SWS and REM sleep, plays a critical role in memory consolidation and retention. SWS is the heavy lifter for declarative memories [such as] the names, dates and facts we learn during the day. REM sleep helps process procedural memories [including] the skills and tasks we pick up. Inadequate sleep has been shown to negatively impact memory consolidation, leading to difficulties in both factual and procedural memory retention. Therefore, prioritizing quality sleep is essential for optimizing learning, memory retention and cognitive performance.

3. Sleep deprivation can impair memory processing and other cognitive processes.

Sleep deprivation can lead to difficulty remembering things, difficulty learning and concentrating, reduced decision-making ability, and poor emotional and behavioral control. Therefore, a formal consensus issued by the Sleep Research Society and the American Academy of Sleep Medicine suggests that getting at least seven hours of sleep each night is crucial for consolidating memories and allowing the brain to function properly. 

Recent research has shown that even one night of sleep deprivation can have a significant impact on brain function. Sleep deprivation can cause neurological damage to the hippocampus, a region of the brain critical for learning and memory. This damage can lead to cognitive impairment and long-term effects on brain health. 

Additionally, sleep loss has been linked to decreased attention, working memory, long-term memory and decision-making. Furthermore, chronic sleep deprivation may lead to an increased risk of cognitive decline and dementia. Therefore, it is important to recognize that even one day of sleep deprivation can have a significant effect on brain function.

4. In addition to genetic influences, age plays a significant role in shaping sleep patterns, and these changes can, in turn, affect memory and cognitive function. 

As people age, there is often a decrease in the total amount of sleep, changes in sleep architecture and an increase in nighttime awakenings. These changes can affect the overall quality of sleep and potentially impact memory consolidation. 

There is also a natural shift in the circadian rhythm as individuals age, leading to changes in sleep-wake cycles, and this shift can result in earlier bedtimes and wake times for older adults, potentially affecting the timing and quality of sleep. Moreover, it is suggested that the effect of slow-wave sleep on memory consolidation tends to be more pronounced in younger people, specifically 18-25 years old. Thus, memory processes change throughout the lifespan, and the relationship between sleep and memory may vary with age.

5. While technology can have a negative impact on sleep and memory, there are also positive advances in technology that may help improve sleep in the future.

Several technological interventions have been developed to improve sleep and, in turn, memory. These include apps that track sleep patterns, offer guided meditations and help adjust sleep schedules to avoid jet lag. 

However, it’s important to note that while sleep technology can be a useful supplement to healthy sleep habits, it should not be relied upon as a quick fix, and establishing and maintaining healthy sleep behaviors is essential to improving sleep quality and memory.