Sleep and Memory
A significant body of scientific research indicates that healthy sleep can have a positive, protective effect on memory.
Studies indicate that sleeping well helps protect the ability to acquire new memories. If you’ve ever tried to cram for a test while short on sleep, you’ve experienced the obstacles that sleep deprivation can have on memory acquisition. Research shows that even a brief lack of sleep can diminish the brain’s capacity to form new memories as part of everyday learning.
Sleep also is important to the ability to recall memories. Research indicates that recall of both short- and long-term memory is impaired by lack of sleep. A sleep-deprived brain is less effective at memory retrieval, while staying well rested can help protect and improve this aspect of memory function.
There is another aspect of the memory process — memory consolidation — that actually occurs during sleep itself. Memory consolidation is the process in which the brain takes new knowledge and converts it to longer-term storage, ready for future recall. Memory consolidation that takes place during sleep not only secures memory for retrieval, but also appears to prepare the brain to accept new information in the next waking day.
Sleep affects different kinds of memory, including both declarative and procedural memories. Declarative memory involves memories related to facts and knowledge, as well as details about individual experiences. Research indicates sleep is critical to the making and storing of declarative memory. Studies also show sleep deprivation and sleep disorders can negatively affect declarative memory.
According to research, the importance of sleep to declarative memory formation exists from the earliest stages of life. Scientists studying memory processing in infants found that babies 6-12 months who took naps at least 30 minutes after learning new behaviors showed better recall than infants who did not sleep.
Procedural memories are task and skill-based memories tied to motor functions and sensory learning. Much of the basic knowledge we need to function on a daily basis — from typing at a computer to driving a car to taking a run at the gym — falls within the category of procedural memory. Procedural memories are often made through repetition and practice, and are recalled without conscious thought. According to research, a routine of high-quality, plentiful sleep is important to motor skill learning and procedural memory.
When you sleep well, you’re making a long-term investment in the health of your memory as you age. Research strongly suggests that high-quality sleep during youth and middle age may help guard against age-related cognitive decline, including problems with memory, many years later. There is also a growing body of scientific evidence that suggests poor quality and insufficient sleep may increase the risks for Alzheimer’s disease and other forms of dementia. Sleep is not the only factor in age-related memory decline, but it appears to be an important one.