This blog post examines why 7 to 8 hours of sleep is truly necessary and whether historical figures who functioned well on less sleep were exceptional cases.
These days, people everywhere are suffering from sleep deprivation. In fact, one study found that Korean high school students average only 5 hours and 27 minutes of sleep per day. This is the result of insufficient rest due to the combination of rapid growth during adolescence and academic stress. Consequently, many teenagers experience chronic fatigue and stress, leading to a vicious cycle where their learning abilities decline as well.
We’ve often heard since childhood that “7 to 8 hours of sleep per day is necessary.” This isn’t mere advice but a scientifically validated recommendation for brain development and physical recovery. The U.S. Food and Drug Administration (FDA) also suggests this range as the appropriate sleep duration for adults. While this statement has clear scientific backing, questions arise about whether this standard applies equally to everyone in real life. In my own case, I often sleep far less than 7 to 8 hours and still function well the next day without major disruption to my daily life. This made me wonder: Is adhering to a strict sleep duration truly necessary to maintain health?
Of course, one might argue, “Skipping a day or two of sleep won’t cause immediate problems, but repeated sleep deprivation will undoubtedly harm your health.” Historically, figures like Napoleon and Edison are known to have slept only 3 to 4 hours a day. They lived without issues despite short sleep and achieved great things. But can such cases be the standard for everyone? Perhaps they were exceptional individuals genetically predisposed to needing less sleep.
What we should truly focus on is whether the cases of these exceptional individuals can be applied equally to the general population. While they may have overcome sleep deprivation in special circumstances, most people find it difficult to maintain physical and mental health without sufficient sleep. In fact, numerous studies show that sleep deprivation weakens the immune system and is closely linked to various chronic diseases in the long term, such as cardiovascular disease, diabetes, and obesity.
Moreover, sleep serves functions beyond mere rest. During sleep, the brain organizes information received during the day and stores what it deems important into long-term memory. This process must occur smoothly to maintain learning ability and creative thinking. Consequently, sleep deprivation can lead to various cognitive issues like decreased concentration, impaired memory, and slowed thinking, directly impacting academic or work performance.
This raises the need to examine whether an ‘optimal sleep duration’ truly exists, what its criteria might be, and what problems arise when it is not met. One of the most representative statistics illustrating the correlation between sleep duration and health is the link between mortality rates and sleep time. According to a globally authoritative research team, individuals averaging 5 hours or less of sleep per day had a 21% higher mortality rate compared to those sleeping 7 hours. Conversely, those sleeping 10 hours or more per day also showed a 36% higher mortality rate. This data indicates that both too little and too much sleep can be detrimental to health. In other words, scientifically, an ‘optimal sleep duration’ clearly exists, and the FDA recommends 7 to 8 hours.
So, what changes occur in the body when this recommended sleep duration is not met? First, during sleep, the body undergoes a process to remove waste products accumulated in the nervous system from daytime activities. If this process isn’t properly completed, brain function declines, and over the long term, it can lead to damage to the nervous system. Furthermore, sleep is the time when the information and emotions accumulated throughout the day are processed. Without sufficient time for this, memory deteriorates, and the flexibility of thought decreases. This inevitably leads to reduced work efficiency and learning ability.
Moreover, sleep deprivation weakens immunity, making one more susceptible to various infectious diseases. It also disrupts hormonal balance, increasing the risk of chronic diseases like obesity and diabetes. In fact, growth hormone and appetite-regulating hormones like ghrelin and leptin are highly sensitive to sleep duration. Lack of sleep increases appetite while decreasing energy expenditure, potentially leading to weight gain. Ultimately, sleep is a crucial physiological factor that governs both physical and mental health.
On the other hand, excessive sleep also negatively impacts health. Recent studies indicate that people who sleep more than 9 hours a day have a higher risk of developing cardiovascular disease, depression, diabetes, and obesity compared to those who do not. Specifically, a 2022 study published in the Journal of the American Heart Association found that individuals sleeping more than 9 hours per day had a 14% higher risk of cardiovascular disease compared to those sleeping 7 hours. It also identified a tendency toward slowed brain activity and increased daytime fatigue. This suggests that while sufficient sleep is important, excessive sleep can actually have adverse effects.
Furthermore, the habit of spending long hours in bed limits physical activity, potentially leading to reduced muscle mass, impaired metabolic function, and worsened mental health. Experts emphasize that for these reasons, both insufficient and excessive sleep should be carefully addressed as major factors harming health.
Based on existing research, it is clear that both too little and too much sleep can negatively impact health. However, in reality, many people suffer from insomnia or fail to get sufficient sleep due to busy schedules involving work or studies. While some rely on medication to address these issues, the ultimate long-term solution begins with improving lifestyle habits. Maintaining a consistent sleep schedule, avoiding excessive caffeine intake before bedtime, and reducing electronic device use are habits that help improve sleep quality. Above all, stress management is an essential element for restful sleep.
Ultimately, sleep is more than just a time to rest the body; it is a crucial factor determining overall quality of life. We live in the 21st century with the keyword ‘well-being’ on our lips, yet we often overlook sleep, the most fundamental aspect of health management. To care for ourselves and live a healthy life, we need to recognize the importance of sleep once again. Maintaining 7 to 8 hours of sleep daily is a small yet powerful start toward a healthier and happier life.
