sleep health time

There is no universal unified standard. Your exclusive healthy sleep time only needs to meet two criteria - no lingering feeling of fatigue within 15 minutes after waking up, and no uncontrolled sudden sleepiness during the day. All the popular "7 hours of golden sleep" and "must sleep before 11 o'clock" are group-level references and are never hard targets for individuals.

I met a 27-year-old e-commerce operator a while ago. In order to get the "7 hours of healthy sleep" mentioned on the Internet, she suddenly adjusted her schedule to go to bed at 11 o'clock and wake up at 6 o'clock. Even if she worked overtime until 10:30 the day before and lay in bed tossing and turning until after 1 o'clock, she still had to set the alarm clock for 6 o'clock to force herself to wake up. I persisted for two months. Not only did I fall asleep on the table at around 3pm every day, but my last physical examination also revealed sinus arrhythmia. When I came to me with the report, I was still confused: "I've slept for 7 hours, why am I still having problems?" ”

In fact, this girl is not the only one. Many people came to me for consultation, clutching the American Academy of Sleep Medicine's sleep duration chart that was circulated on the Internet. They insisted that they had health problems if they didn't sleep enough for 7 hours. I often show that table to consultants: 14-17 hours is recommended for newborns, 10-13 hours for preschoolers, 9-12 hours for school-age children, 8-10 hours for teenagers, 7-9 hours for adults between 18 and 64 years old, and 7-8 hours for seniors over 65 years old. But every time I give it, I have to add that this is a range calculated from a large sample that is suitable for most people. It does not mean that missing 10 minutes of sleep will cause problems.

In the past two years, the field of behavioral sleep medicine has actually been weakening the "duration theory", and many researchers pay more attention to sleep quality and rhythm stability. For example, short sleepers who are born with DEC2 gene mutations only need 4 to 6 hours of sleep a day to fully restore their energy. Their physical functions are no different from those of people who sleep for 8 hours. Such people account for about 1% of the population. Those friends around you who stay up until 1 o'clock every day and are still active as usual at 7 o'clock in the morning are most likely carriers of this type of gene. Staying up late really won't harm your body. If you don't have this gene and learn it hard, you are just looking for trouble.

You must have had this experience too, right? I had nothing to do on the weekend and slept for 10 hours. When I woke up, I was so dizzy that I didn’t even have the energy to check my phone. Instead, I had to catch up on projects during the workday and only slept for 6 and a half hours. After I woke up, I felt refreshed and worked more efficiently than usual. To put it bluntly, the sleep cycle is at work. A person's sleep cycle is about 90 minutes a night. Each cycle will go through three stages of light sleep, deep sleep, and REM sleep. If you happen to be woken up by the alarm clock during the deep sleep stage, even if you have slept for the so-called 7 hours, it will be as uncomfortable as being beaten. If you happen to wake up in the light sleep stage at the end of the cycle, half an hour less sleep will have no effect.

You must have seen two statements that are making a lot of noise on the Internet right now. One is that "sleeping less than 7 hours a day will increase the risk of Alzheimer's disease and diabetes." The other is that "as long as you feel energetic enough, you can sleep as long as you want." In fact, both statements are correct, but the applicable scenarios are different. The former conclusion is a group trend based on statistics from hundreds of thousands of samples. For 99% of ordinary people who do not have the short-sleep gene, the risk of chronic diseases if they sleep less than 6 hours for a long time will indeed be about 20% higher than that of people who get enough sleep. However, this conclusion is not 100% true for a single individual. The latter statement is closer to individual feelings, but it has also become an excuse for many people to stay up late - if you sleep for 5 hours a day, can nod off during meetings during the day, and can't suppress your sleepiness even after drinking three cups of coffee, don't insist on saying that you are a short sleeper. Your body's reaction is more honest than anything else.

I have been doing sleep consulting for three years, and the methods I recommend to everyone to find their own healthy sleep time are very simple. You don’t need to buy a sleep bracelet worth hundreds of dollars, and you don’t need to keep a sleep diary every day: just find a long vacation when you don’t have to work, don’t drink alcohol or strong tea, don’t watch short videos for two hours before going to bed, don’t set an alarm clock, sleep naturally and wake up naturally, measure it for 3 days in a row, take the average sleep duration, and combine it with your energy state after waking up, that is your healthy sleep time. The most exaggerated consultant I have ever seen is a 32-year-old programmer. The measured healthy sleep time is 6 hours and 10 minutes. He used to sleep for 7 hours and lay down for half an hour to relax every day when he woke up. Now he sleeps for 6 hours and 10 minutes. Instead, he can sit up and start work every day when he wakes up.

To be honest, I have always felt that sleeping is the most instinctive thing for human beings. I don’t know when to start, and it is framed by various standards as KPIs to be completed. I have to fall asleep at 11 o’clock, and I have to make up for 7 hours. If it is less, I will be anxious for half a day. How can there be so many necessities? How comfortable you are and whether you have energy during the day are more reliable than the numbers given by any experts, right? After all, sleep is meant for relaxation. If you end up with anxiety and insomnia just to get enough so-called "healthy time," that's really putting the cart before the horse.