IQ and Sleep: How Sleep Affects IQ & Cognitive Performance

The connection between IQ and sleep can be best described as indirect. Although sleeping more doesn’t directly increase IQ, sleep is crucial for optimal cognitive performance. Therefore, consistently getting sufficient, quality sleep may help you perform better on an IQ test, leading to a higher score.

In this article, we’ll explore the link between IQ and sleep in adults and children alike, discover how sleep impacts brain health, and share tips for restful, brain-boosting sleep. Let’s begin!

Key Takeaways

• IQ is a score derived from a standardized test that denotes a person’s intellectual abilities.
• Sleep is essential for brain health, as it supports optimal cognitive function and performance.
• Sleep deprivation may reduce your IQ by negatively affecting your attention, memory, and other cognitive functions that may impact your test results.
• For maximum cognitive performance, you should consistently get 6–8 hours of sleep per night.
• Sticking to a bedtime routine, preparing your environment for sleep, and leading a healthy lifestyle can help you get better sleep and improve your cognitive abilities.

What is IQ?

IQ—or intelligence quotient—is a numerical value that describes an individual’s intellectual and cognitive abilities in relation to their peers.

An IQ score is derived by taking a standardized IQ test, such as the Stanford-Binet test, that measures various cognitive skills. These range from logical reasoning and pattern recognition to problem-solving, decision-making, and beyond.

Most tests use a score of 100 as the average IQ, with the majority of people scoring between 85 and 115. While anything above 115 is considered an above-average IQ, a score of 130 or higher denotes high intelligence. Meanwhile, scores below 71 signal a low IQ and are associated with impaired cognitive functioning.

IQ scores can be affected by numerous factors, such as age, genetics, and stress. Furthermore, they can be applied in various contexts, including education (e.g., to identify the need for special education or, conversely, a gifted program), career development, and research.

Before we explore the link between IQ and sleep, let’s learn how sleep and rest affect brain health and cognitive function.

The Importance of Sleep and Rest for Brain Health

Sleep and rest play a critical role in maintaining optimal brain health. Besides allowing the body to recharge, quality sleep enhances cognitive performance, supports memory consolidation, and promotes healthy brain development.

While you’re asleep, the brain remains active and cycles through two sleep stages:

• Non-rapid eye movement (NREM) sleep, characterized by slowed brain waves and spikes in brain activity (sleep spindles)
• Rapid eye movement (REM) sleep, marked by increased brain activity, leading to vivid dreaming

NREM sleep is further divided into three stages. Sleep spindles can occur at any time during NREM sleep, but they tend to appear most frequently during the second stage, which accounts for roughly 45% of the total sleep time. These short bursts of brain activity during sleep have been the focus of several studies on IQ and sleep.

Researchers from Western University, for example, found that sleep spindles are biomarkers of intelligence. Specifically, they are connected to cognitive performance and fluid intelligence, marked by high reasoning abilities. Interestingly, the study suggests that sleep quality does not affect the link between fluid intelligence and sleep spindles.

The third stage of NREM sleep—deep sleep or slow-wave sleep (SWS)—is also imperative to brain health. During this stage, the brain activity becomes slow but powerful; in addition to sleep spindles, the brain also produces restorative delta waves. Delta sleep may also promote insight and creative thinking.

Meanwhile, during REM sleep, the brain waves closely resemble those of wakefulness, indicating intense cognitive processing. While you may dream at any stage, vivid dreams are most common when you enter REM sleep. This stage is particularly critical for memory consolidation, emotional processing, and overall brain development.

Next, let’s discuss the connection between IQ and sleep deprivation.

How Does Sleep Deprivation Affect IQ?

Sleep deprivation can negatively affect IQ, though not permanently. Sleep deprivation—or a lack of quality sleep—may impair your working memory, attention span, and other cognitive functions. Consequently, it may lead to a lower IQ score. For this reason, you should ideally take IQ tests when you’re well-rested.

Getting enough quality sleep is especially crucial for children. Sleep deficiency can not only lead to negative outcomes, such as poor school performance, but also impact brain and intelligence development, as suggested by Wang et al.

The study shows that there’s a link between low IQ and sleep deprivation in primary school students. Severe sleep deprivation was found to decrease all scores, including verbal IQ (VIQ), performance IQ (PIQ), full-scale IQ, verbal comprehension, memory, and attention.

Moreover, high fluid intelligence is often thought to offer protection against daily life stressors, yet it doesn’t make you immune to the adverse cognitive effects of sleep loss.

On the contrary, Balter et al. found that while high fluid intelligence generally makes people better at arithmetic calculations and tasks requiring episodic memory, it also makes them more vulnerable to the effects of sleep deprivation.

The results reveal that sleep loss significantly impacts the arithmetic ability, spatial working memory, and episodic memory of those with high fluid intelligence. However, fluid intelligence doesn’t necessarily correlate with worse cognitive performance after sleep loss compared to the baseline.

Instead, the study demonstrates that sleep insufficiency mitigates the usual cognitive benefits of fluid intelligence. While a lack of quality sleep can negatively affect anyone’s IQ and cognitive function, its effects may be more visible in those with a high baseline capacity.

With this in mind, let’s see if there’s a correlation between high IQ and sleep duration and if sleeping more can boost your brain power.

Does Sleeping More Increase IQ?

Sleeping more may increase IQ by helping you maintain optimal brain function, improving cognitive performance, and enhancing your ability to take in and process new information. While a few extra hours of sleep might not increase your IQ directly, getting sufficient sleep may help you perform better at cognitive tasks, including those on an IQ test.

Researchers from the Seoul National University College of Medicine found a significant association between children’s IQ and sleep duration in a sex-dependent manner. Unlike boys, girls did not demonstrate a correlation between the duration of sleep and IQ scores.

Meanwhile, boys who slept longer showed improved verbal performance and total IQ scores. Those sleeping less than 8 hours per night scored 10 points lower than boys who slept 10 hours or more.

However, longer sleep duration doesn’t necessarily increase IQ. In fact, a study by researchers from the University Children's Hospital Zurich suggests that children who sleep less on weekends tend to have higher intelligence scores than those who sleep longer. The study shows that each hour of shorter sleep duration increases the fluid IQ score by approximately 6 points.

Furthermore, higher IQ scores in children were correlated with daytime cognitive and nighttime efficiency. The effects of sleep on the brain and intelligence, therefore, may depend more on the quality of sleep rather than sleep duration, which may explain why high-scoring children slept less than their peers.

In other words, how much you sleep may not be as important as how well you sleep. Getting quality, uninterrupted sleep may have a greater impact on your cognitive abilities than sleep duration. Nonetheless, consistently sleeping less than your body needs to function optimally can negatively impact your cognitive function and overall health.

Optimal Amount of Sleep for Maximum Cognitive Performance

The optimal amount of sleep for maximum cognitive performance is between six and eight hours. A study done by Tai et al. found that people who sleep 6–8 hours per night have higher gray matter volume in 46 brain regions, including hippocampi, right frontal pole, and orbitofrontal cortex, resulting in greater cognition.

However, the recommended amount of sleep also differs based on individual factors, such as age. While preschool children need 10–13 hours of sleep, for example, teens require 8–10 hours. Adults, regardless of their age, should aim to get around 7 hours of continuous sleep. Generally, women need to sleep 10–20 minutes longer than men.

Importantly, sleeping too much or too little can be detrimental to your brain health, increasing the risk of cognitive decline. Unfortunately, not everyone is lucky enough to get the recommended amount of sleep consistently.

On that note, let’s explore the connection between IQ and sleep disorders.

How Do Sleep Disorders Affect IQ and the Brain?

Sleep disorders, such as insomnia, narcolepsy, and sleep apnea, can have a significant negative impact on brain function, which might also affect your IQ. When it comes to sleep and IQ, the key problem with sleep disorders is that they disrupt the sleep patterns required to maintain optimal brain function. Therefore, they may increase the risk of cognitive impairment.

For example, sleep apnea, a sleep disorder that causes pauses in breathing during sleep, can lead to memory problems. This shouldn’t come as a surprise, given that stopped breathing may interrupt both NREM and REM sleep, which are crucial for memory consolidation.

Snoring is a common symptom of sleep-related breathing disorders, including sleep apnea. Researchers from the University of Virginia Health System found that children with sleep disorders are at risk of intellectual impairment; snoring during sleep can affect children’s IQ at a similar level to lead exposure.

Reduced memory is also a risk associated with other sleep disorders, including insomnia, which is marked by difficulty falling or staying asleep. Moreover, sleep disorders can lead to excessive daytime sleepiness, which can affect your focus and attention.

Narcolepsy is a chronic disorder that impacts REM sleep and hinders the brain’s ability to control sleep-wake cycles, causing people to suffer from “sleep attacks” and excessive daytime sleepiness.

Interestingly, research suggests that high IQ can reduce the negative impact of narcolepsy. A study by Yoon et al. found that while people with this disorder are prone to visual working memory and visual attention deficits, higher IQ reduces the likelihood of cognitive dysfunction and depressive mood.

However, high intelligence can make you more susceptible to sleep disorders. Researchers from the Université de Montréal found that gifted children display reduced sleep efficiency, with their parents reporting more clinically significant sleep problems than those of typically developing children.

3 Effective Ways to Get Better Sleep and Boost Your Cognitive Capabilities

You can get better sleep and boost your cognitive capabilities by establishing a good sleep routine, creating a peaceful sleep environment, and building healthy lifestyle habits.

Let’s dissect each of these strategies:

#1. Create a Sleep Routine

Designing and sticking to a bedtime routine is key to consistently getting quality sleep and improving sleep efficiency. At the very least, you should aim to go to bed and wake up around the same time, weekends included, to maintain a healthy circadian rhythm.

Here are some other ideas you can incorporate into your bedtime routine to prepare your mind and body for sleep:

• Journal
• Meditate
• Drink herbal tea
• Read a light-hearted book
• Take a warm bath or shower
• Build a nighttime skincare routine
• Listen to calming music or nature sounds
• Reflect on your day and make a gratitude list

For best results, don’t cram too many steps into your bedtime routine; it should be simple enough for you to follow every night for 30–60 minutes before sleep.

#2. Optimize Your Sleep Environment

Preparing your environment for sleep and relaxation can help you fall asleep faster and ensure you don’t wake up at night due to distractions, such as uncomfortable room temperature.

To create the ideal sleep environment, consider:

• Keeping your bedroom clutter-free
• Adding white noise (e.g., a fan) if the room is noisy or too quiet
• Using blackout curtains or an eye mask to block disruptive lights
• Using a diffuser or a room spray with soothing scents, such as lavender
• Leaving your phone outside the bedroom or turning Do Not Disturb mode on
• Getting a humidifier or a dehumidifier to maintain a comfortable moisture level
• Investing in a good mattress, soft sheets, and blankets, as well as a comfortable pillow

To create optimal conditions for peaceful sleep, keep your bedroom cool (around 65–68°F or 15.6–20°C) and ensure proper ventilation.

#3. Adopt Healthy Lifestyle Habits

Adopting healthier lifestyle habits can significantly improve the quality of sleep over time.

Some simple lifestyle changes you can make for better sleep include:

• Eating a nutritious diet
• Getting regular exercise
• Avoiding long or frequent daytime naps
• Avoiding heavy meals, alcohol, and caffeine before bedtime
• Using your bed only for sleep (e.g., avoiding working from bed)
• Limiting exposure to screens (smartphones, computers, etc.) before sleep
• Practicing stress management techniques, such as deep breathing exercises

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Final Thoughts

Hopefully, this article helped you not only gain insight into the intricate connection between IQ and sleep but also learn how to improve your sleep quality to unlock your full cognitive potential.

At the end of the day, sleep is vital for a healthy mind and body. Whether you’re looking to boost your concentration or improve your memory, quality sleep is one of the most powerful tools for enhancing and maintaining cognitive performance.

Therefore, you should never compromise on it; consistently prioritizing restful sleep is a long-term investment in your overall well-being, including brain health. Sweet dreams!