Reference News Network, September 19 report: According to the U.S. "Popular Science" magazine website on September 9, ideally, we should wake up feeling refreshed and ready for a new day. But you may not feel that way when the alarm rings; your eyes might be too heavy to open, and your body seems to be firmly attracted by the bed's "magnetic field."

Let's look at what is called the "90-minute sleep cycle method," which is said to help you wake up energetic. The core idea is to precisely plan sleep and wake-up times so that sleep cycles in 90-minute units. The specific operation is: calculate the ideal bedtime by working backward from your target wake-up time in 90-minute units. For example, if you want to wake up at 7 a.m., you can choose to go to bed at 10 p.m., completing six 90-minute cycles (9 hours of sleep), or 11:30 p.m., completing five cycles (7.5 hours of sleep).

According to a 2024 survey by the American Academy of Sleep Medicine, this practice has become popular on social media, with nearly one in ten American adults trying it. But does this "sleep secret" really have scientific basis?

The logic behind the "90-minute sleep cycle method" is simple: waking up at the end of a complete cycle feels more refreshing than being suddenly awakened from deep sleep.

The problem is that real sleep is much more complex than described in textbooks. Dr. Andrea M. K. Momose, a sleep physician, explained that although the average sleep cycle is about 90 minutes, its actual length varies from person to person.

Even for the same person, the duration of a sleep cycle is not always the same. She said, "Factors such as stress, alcohol, illness, and even the time you go to bed can affect your sleep cycle, so this method cannot truly guarantee that you won't feel groggy when you wake up."

Sleep psychologist Jada Wu (translated) also agrees that the "90-minute sleep cycle method" lacks scientific basis. She said, "The length of the sleep cycle depends on multiple factors such as your sleep needs that night, hormone levels, sleep environment, diet, and surroundings. It is impossible to predict or adjust a cycle to exactly 90 minutes."

As the night progresses, sleep cycles tend to get longer. The first sleep cycle ranges from 70 to 100 minutes, while subsequent cycles last 90 to 120 minutes.

Theoretically, the "90-minute sleep cycle method" claims to help you avoid waking up from the deep sleep stage, which is the hardest to awaken from, and thus people often feel extremely tired when waking up during this stage. However, Wu explained that the method lacks scientific support because sleep cycles change as the night progresses: the first half of the night is dominated by deep sleep, while the second half gradually shifts to rapid eye movement (REM) sleep. She said, "In fact, healthy sleepers typically do not enter deep sleep during the latter half of the night — so people who are awakened in the morning are not actually in the deep sleep stage."

Momose said, "Instead of relying on these techniques, it's better to prioritize establishing a regular sleep schedule, allowing your body to naturally wake up at the end of a sleep cycle." This means maintaining a consistent bedtime and wake-up time — even on weekends.

Dr. Fozia Siddiqui, Medical Director of the Sentara RMH Medical Center in the U.S., said that studies show adults aged 18 to 65 need 7 to 9 hours of sleep. Unless you are one of the lucky few who can feel energized with only 6 hours or less of sleep.

Siddiqui and Momose both recommend avoiding electronic screens before bed and keeping the room quiet and comfortable to improve sleep quality. Also, limit the intake of sleep disruptors like alcohol and caffeine in the evening.

Wu pointed out that even with good sleep quality, feeling groggy for 20 to 30 minutes after waking is normal. Momose said that natural morning light can effectively eliminate drowsiness — it signals the brain to reduce melatonin secretion and increase cortisol levels, thus resetting the biological clock and increasing alertness.

The "90-minute sleep cycle method" may seem scientific, but it doesn't hold up under scrutiny. Experts agree that maintaining good sleep hygiene is more effective than chasing calculated bedtime schedules. (Translated by Zhang Lin)

Original article: https://www.toutiao.com/article/7551707163996013096/

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