Fact Check: Does 7-9 Hours of Sleep Improve Health and Cognitive Function?

The National Sleep Foundation (NSF) has long advocated for the importance of sleep, claiming that getting 7-9 hours of sleep per night improves overall health and cognitive function.

This claim, prominently featured on their website (source), aligns with widely accepted sleep guidelines. But how accurate is this assertion? Let’s examine the evidence behind the NSF’s claim and explore whether 7-9 hours of sleep truly delivers the benefits they describe.

The Claim: 7-9 Hours of Sleep Improves Health and Cognitive Function

Fact Check: The Claim is True

The Evidence: What Does the Research Say?

1. Cognitive Function and Sleep Duration
   Numerous studies have linked adequate sleep to improved cognitive function, including memory, problem-solving, and decision-making. A 2018 study published in Sleep Medicine Reviews found that 7-9 hours of sleep is associated with optimal cognitive performance, while both shorter and longer sleep durations were linked to declines in attention, memory, and executive function (source).
   Additionally, a 2021 study in Nature Communications demonstrated that sleep deprivation negatively impacts the brain’s ability to consolidate memories and process information, further supporting the NSF’s claim (source).
   
2. Physical Health and Sleep Duration
   The NSF’s claim about improved overall health is also well-supported. Research shows that insufficient sleep is associated with a higher risk of chronic conditions such as obesity, diabetes, cardiovascular disease, and weakened immune function. A 2015 study in Sleep found that individuals who consistently slept 7-9 hours per night had lower rates of these health issues compared to those who slept less than 6 hours or more than 10 hours (source).
   Furthermore, the American Heart Association has endorsed 7-9 hours of sleep as part of its “Life’s Essential 8” for cardiovascular health (source).
   
3. Mental Health and Sleep Duration
   Sleep is also critical for mental health. A 2020 meta-analysis in JAMA Psychiatry found that insufficient sleep is strongly associated with an increased risk of depression, anxiety, and other mood disorders. The study highlighted that 7-9 hours of sleep is protective against these conditions (source).

Are There Exceptions to the 7-9 Hour Rule?

While the NSF’s recommendation is broadly supported, individual sleep needs can vary.

Some people may feel rested with slightly less sleep, while others may require more. Genetics, age, lifestyle, and underlying health conditions can all influence how much sleep a person needs.

For example, older adults may require slightly less sleep, while teenagers and young adults often need closer to 9 hours for optimal functioning (source).

Potential Risks of Too Much or Too Little Sleep

The NSF’s recommendation of 7-9 hours is not arbitrary; it is based on evidence that both insufficient and excessive sleep can have negative consequences.

• Insufficient Sleep: Chronic sleep deprivation (less than 6 hours per night) is linked to impaired cognitive function, increased inflammation, and a higher risk of chronic diseases (source).
• Excessive Sleep: Regularly sleeping more than 9 hours per night has been associated with health issues such as depression, cardiovascular disease, and impaired glucose metabolism (source).

Conclusion: Is the NSF’s Claim Accurate?

The National Sleep Foundation’s claim that 7-9 hours of sleep improves overall health and cognitive function is well-supported by scientific evidence. Research consistently shows that this sleep range is associated with better physical health, enhanced cognitive performance, and improved mental well-being. While individual needs may vary slightly, the 7-9 hour guideline is a reliable benchmark for most adults.

If you’re struggling to meet this recommendation, consider adopting healthy sleep habits, such as maintaining a consistent sleep schedule, limiting screen time before bed, and creating a restful sleep environment. Prioritizing sleep is one of the simplest yet most effective ways to improve your overall health and quality of life.

References:

1. National Sleep Foundation: Sleep and Achieving Goals
2. Sleep Medicine Reviews: Optimal Sleep Duration and Cognitive Function
3. Nature Communications: Sleep Deprivation and Memory
4. Sleep Journal: Sleep Duration and Chronic Disease Risk
5. American Heart Association: Life’s Essential 8
6. JAMA Psychiatry: Sleep and Mental Health
7. CDC: How Much Sleep Do I Need?
8. National Institutes of Health: Risks of Insufficient Sleep
9. National Institutes of Health: Risks of Excessive Sleep