Elderly people, sleeping too much can lead to a stroke... How many hours of sleep are appropriate per day?

Adequate sleep is essential for a healthy life. However, excessive sleep can negatively impact health. This article introduces the physical problems that excessive sleep can cause, supported by medical evidence.

◇ Sleeping too much increases the risk of heart disease. A joint doctoral research study by the University of Sheffield in the UK and Beijing Union Medical College examined the relationship between sleep duration and the risk of cardiovascular disease and death among 116,632 adults aged 35 to 70 from 21 countries across seven regions worldwide, including North America, Europe, the Middle East, and Asia, with varying income levels. The research team analyzed the data while considering factors that could influence the results, such as age, gender, education level, smoking, alcohol consumption, and family history of cardiovascular disease. The findings showed that participants who slept an average of 6 to 8 hours per day had the lowest risk of cardiovascular disease and death. Sleeping 8 to 9 hours, 9 to 10 hours, or more than 10 hours increased the risk of cardiovascular disease and death by 5%, 17%, and 41%, respectively.

◇ Stroke The risk of stroke increases. According to a study by the University of Cambridge in the UK, elderly individuals who sleep more than 8 hours a day have a 50% higher risk of stroke compared to those who do not. The researchers analyzed the relationship between sleep and heart health over 9 years and 5 months, involving approximately 10,000 adults aged 42 to 81. When sleep is insufficient, abnormalities occur in the body's metabolic activities, leading to an increase in the stress hormone cortisol. As a result, blood pressure rises and the risk of stroke also increases.

Excessive sleep and memory decline can negatively affect brain health and may impair memory. A research team from University College London (UCL) in the UK measured usual sleep duration and conducted memory-related tests on approximately 400,000 people. The memory test involved showing six cards, having participants memorize their positions, and then recalling them. As a result, people who slept 9 hours had a 5% higher chance of making mistakes compared to those who slept 7 hours. When considering factors such as age and gender, the difference was about 2%. Additionally, individuals who slept 10 hours had an 11% higher probability of errors compared to those who slept 7 hours. Adjusting for age and gender, this difference was 6%. The research team stated, "This study shows that sleeping too long can also negatively impact memory."

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Like memory decline, cognitive function can also deteriorate. A research team from Western University in Canada analyzed over 40,000 participants to study the relationship between sleep duration and cognitive function. As a result, those who slept 7 to 8 hours daily had the highest cognitive function. Conversely, sleeping more than 8 hours a day was associated with decreased cognitive function. The study found that participants' reasoning and language abilities were most affected by sleep. The research team stated, "The optimal sleep duration to keep the brain in the best condition is 7 to 8 hours per day." The findings were published in the International Journal of Sleep Medicine, 'SLEEP'.

◇Different Appropriate Sleep Durations by Age There are varying opinions among scholars regarding the appropriate amount of sleep. The most commonly used standard for sleep duration is the age-specific sleep times proposed by the American Sleep Foundation. The foundation annually gathers opinions from experts across various fields such as anatomy, physiology, neurology, and geriatrics to announce recommended sleep durations for different age groups. According to this standard, ▲newborns aged 0-3 months should sleep 14-17 hours, ▲infants aged 4-11 months should sleep 12-15 hours, ▲toddlers aged 1-2 years should sleep 11-14 hours, ▲preschoolers aged 3-5 years should sleep 10-13 hours, ▲elementary school students aged 6-13 years should sleep 9-11 hours, ▲middle school students aged 14-17 years should sleep 8-10 hours, ▲high school and college students aged 18-25 years should sleep 7-9 hours, ▲adults aged 26-64 years should sleep 7-9 hours, and ▲senior citizens aged 65 and above should sleep 7-8 hours. All these durations include total sleep time, including naps.