Memory and Sleep

Sleep and memory are closely connected. Studies show that sleep is necessary to prepare the brain for learning and retaining new information. Without enough consistent, high-quality sleep, the brain has a difficult time consolidating memories. We explore research on sleep and memory and share tips for improving your sleep.

What’s the Link Between Sleep and Memory?

While a person is awake, the brain acquires and stores new information in a process known as encoding. Encoded information may be easily forgotten until it has been consolidated. During the process of memory consolidation, the brain turns important information into long-term memories.

Sleep allows the brain to consolidate memories without being distracted by waking life. The brain must assess information, remembering what is important and forgetting the rest.

Experts believe that consolidation takes place across multiple brain cell processes that occur in waves at different times. These waves stabilize and strengthen memories. Long-term memories may go through the consolidation process each time they are reactivated.

Sleep Stages and Memory

There are two types of sleep: rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. NREM sleep consists of two lighter sleep stages and a third stage known as deep or slow-wave sleep. Most people cycle through all three stages of NREM followed by one stage of REM sleep multiple times each night.

Each NREM stage affects the body in different ways, and each plays a role in memory formation. Sleep researchers theorize that the brain consolidates a different type of memory during each sleep stage. For example, slow-wave sleep is believed to be used to process new facts and information such as names and dates.

  • Stage 1: This stage represents the transition from waking life to sleep. It is brief and light. People in stage 1 are easy to wake up and often do not remember falling asleep.
  • Stage 2: Middle-aged adults spend about half of the night in stage 2 sleep. Studies show that more time spent in stage 2 is associated with motor skill improvement, while less stage 2 sleep impairs motor memory. This stage may also be involved in remembering words and images.
  • Stage 3: Stage 3 sleep is high-quality sleep people need to feel refreshed. This stage also plays a crucial role in memory consolidation. Studies show that getting more slow-wave sleep helps people remember new information. Experts believe old memories may be reactivated and stored for the long term during this stage.

After stage 3, a person enters REM sleep. During this stage, the sleeper is unable to move, and they may experience vivid dreams. Experts are not in agreement on REM sleep’s exact purpose. Some scientists believe that the brain identifies which memories to consolidate and which to discard during REM sleep.

REM sleep may also be involved in storing emotional memories and remembering how to perform complex motor activities. Some studies show that getting more REM sleep enhances creative thinking, and people who are required to think creatively spend more time in the REM stage. 

How Sleep Deprivation Affects Memory

Insufficient sleep can cause a variety of cognitive and emotional problems, including memory loss, difficulty learning new information, mood swings, and poor decision making.

Both long-term and short-term sleep deprivation negatively impact cognitive performance. Studies show that missing just a few hours of sleep can make it difficult to concentrate the next day. Research indicates that some aspects of memory are not affected by sleep loss, but others are.

Even falling short on certain parts of the sleep cycle can impact memory consolidation. For example, a lack of REM sleep might make it harder to memorize complex tasks. People who lose too much stage 2 sleep may have trouble remembering how to perform simpler motor tasks.

Missing out on sleep may cause children to experience memory and learning difficulties. Kids who do not get adequate sleep are more likely to have trouble remembering verbal information. In contrast, napping may make young children better at retaining information and learning new motor skills.

Adequate sleep is necessary for kids to reach important milestones in their cognitive development. Adults should also prioritize sleep to stay healthy and alert. Although sleep needs vary among adults, experts have developed a series of age-based sleep recommendations based on the average individual.

Age Group
Age In Years
Recommended Amount of Sleep Per 24 Hours

Newborns

0 to 3 months

14 to 17 hours

Infant

4 to 11 months

12 to 15 hours

Toddler

1 to 2 years

11 to 14 years

Preschool

3 to 5 years

10 to 13 hours

School age

6 to 12 years

9 to 11 hours

Teen

13 to 18 years

8 to 10 hours

Young adult

18 to 25 years

7 to 9 years

Adult

26 to 64 years

7 to 9 hours

Older adult

65+

7 to 8 hours

If you are having trouble getting enough sleep and struggling with memory problems, contact your doctor. Memory loss is associated with many sleep disorders, including insomnia, narcolepsy, nightmare disorders, and some forms of sleep apnea.

How Sleep Apnea and Memory Loss Are Connected

Sleep apnea and memory loss often occur together because individuals with untreated sleep apnea do not get the restorative, high-quality sleep required for memory consolidation.

Obstructive sleep apnea (OSA) is a common sleep disorder that affects breathing. In OSA, a sleeping person’s airway collapses, causing them to briefly breathe shallowly or stop breathing. As a result, they may wake up choking or gasping for air, and snore frequently. People with OSA often feel tired during the day because they wake up during the night. 

Individuals who have OSA are also at a higher risk for developing memory-related conditions like cognitive impairment and dementia. One study found that people with sleep-related breathing disorders, like sleep apnea, were 26% more likely to develop dementia or cognitive problems.

The reason OSA triggers or worsens memory loss is unclear. Some experts believe that low blood oxygen levels caused by the disorder harm the brain. However, most lapses in breathing due to sleep apnea occur during sleep stages 1 and 2, and during REM sleep. Stage 2 and REM sleep are both critical to memory consolidation.

When to Talk to a Doctor

Everyone forgets things on occasion, especially after sleeping less than usual. Memory loss can also be a part of the aging process. However, some older adults are more forgetful than others. They may be experiencing a condition called mild cognitive impairment (MCI).

MCI has many causes, including Alzheimer’s disease, other medical conditions, and certain medications. If you are concerned about memory loss, contact your health care provider. Let them know if you are experiencing symptoms of MCI, including:

  • Losing or forgetting items
  • Missing important dates or appointments
  • Frequently struggling to remember words

A doctor can also help you address any sleep problems that may be affecting your memory. While it is not uncommon to have trouble sleeping now and again, some symptoms warrant a call to your doctor:

  • Loud, frequent snoring
  • Choking or gasping in your sleep 
  • Feeling sleepy or fatigued during the day 
  • Mood changes like depression or anxiety 
  • Poor performance at work or school due to fatigue

Sleep Tips

Practicing good sleep habits may also help you get better rest. Try these tips for improving your sleep.

  • Maintain a consistent schedule: Go to sleep at the same time every night and wake up at the same time each morning.
  • Learn to associate your bed with sleep: Use your bed for sleeping and sex only. Avoid working, eating, or performing other activities in bed.
  • Let go of stress: Meditation, yoga, and breathing exercises can be a great way to de-stress before bed. 
  • Watch what you drink: Avoid drinking alcohol or caffeine before bed.
  • Get comfortable: Optimize your bedroom for sleep. Keep the room quiet and as dark as possible. Maintain a comfortable temperature that is not too hot or too cold.

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