In February 1972, Michel Siffre crawled into a completely isolated cave in southwest Texas, where he spent six months without seeing sunlight.
Siffre was a French scientist and a pioneer in the study of biological rhythms, particularly the circadian rhythm that controls the sleep-wake cycle in humans. His mission in the cave was to study how this rhythm works.
Siffre's life in the cave was extremely simple. He lived in a tent on a wooden platform with a small bed, a chair, and a telephone to communicate with his team on the surface. The cave was equipped with incandescent lights that provided dim lighting. There were no clocks or calendars, so he had no way of telling time or distinguishing between day and night. This was how he spent six months alone in the cave.
During that time, Siffre's biological clock took over his life. He later wrote in his notes: "My sleep was perfect! My body would choose when to sleep and eat on its own." They found that his sleep-wake cycle was not exactly 24 hours like people on the surface, but slightly longer - 24 hours and 30 minutes. Several times, Siffre's body switched to a 48-hour sleep-wake cycle, naturally staying awake for 36 hours and sleeping for 12 hours.
Siffre's work with his team sparked scientific interest in sleep research, leading to the establishment of sleep research centers at famous universities such as Harvard University and the University of Pennsylvania. We spend about one-third of our lives sleeping, and it is hard to believe that such an important topic has only made significant progress in recent years. In this article, we will share the science of sleep, how it works, why many people are suffering from "sleep deprivation" without realizing it, and provide practical tips for getting better sleep with Sweetnight's best luxury mattress.
Lack of Sleep: How Much Sleep Do You Really Need?
How much sleep do we need? To answer this question, let's look at an experiment conducted by the University of Pennsylvania and Washington State University.
Researchers gathered 48 healthy male and female subjects and divided them into four groups. The first group drew the short straw and went without sleep for three days and two nights. The second group slept four hours a night, the third group slept six hours a night, and the fourth group slept eight hours a night. The four, six, and eight-hour sleep patterns had to be maintained for two weeks. During the entire experiment, researchers tested subjects' physical and mental performance.
During the experiment, subjects who slept eight hours a night did not show any cognitive decline, attention deficits, or reduced motor function, while those who slept four or six hours a night showed a decline in performance. The group that slept four hours performed the worst, but the group that slept six hours did not perform much better. Finally, the experiment found two issues worth noting:
Firstly, sleep debt accumulates over time. Researchers told us: "Sleep debt has a neurobiological cost that accumulates over time." In the first week of the experiment, 25% of the group that slept six hours a night would doze off at irregular intervals. By the second week, their performance was similar to that of the group that had not slept for two days. To repeat: if you only sleep six hours a night for two weeks in a row, your mental and physical performance will decline to the level of being awake for 48 hours in a row.
Secondly, subjects were unaware of their declining performance. When subjects rated their own performance, they believed that their performance decline was temporary and would gradually recover. In fact, their performance got worse every day. In other words, when faced with "sleep deprivation," we cannot judge our own declining performance, even when we are experiencing it ourselves. In the real world, bright offices, social conversations, caffeine, and other factors can make you feel completely awake even if your actual performance is not good.
According to researchers' estimates, sleep deprivation in the United States alone causes companies to lose more than $100 billion in productivity. Gregory Belenky, director of the Sleep Research Center at Washington State University, said: "Unless your job doesn't require much thinking, you need more awake time at the cost of reduced work efficiency."
So when does sleep debt accumulate? When does it start to decline and deteriorate? According to extensive research, the critical point is usually at seven or 7.5 hours. Generally speaking, experts believe that 95% of adults need 7-9 hours of sleep per night, and those who sleep less than seven hours will experience a decline in physical and mental performance. Therefore, most adults should aim for eight hours of sleep per night. Children, teenagers, and older adults usually need more.
The Mystery of Sleep: Sleep Cycles
Sleep quality is determined by the sleep cycle process. There are two important components of the sleep cycle:
Slow-wave sleep (deep sleep)
REM sleep (rapid eye movement sleep)
During slow-wave sleep, the body relaxes, blood pressure drops, breathing becomes more regular, and the brain becomes less responsive to external stimuli. This stage is critical for repairing the body. During slow-wave sleep, the pituitary gland releases growth hormone to stimulate tissue growth and muscle repair. Researchers also believe that the immune system is repaired during this stage. If you are an athlete, slow-wave sleep is even more critical. You may have heard that some professional athletes sleep 11-12 hours a night.
If slow-wave sleep is responsible for repairing the body, then REM sleep is responsible for repairing the mind. The brain is relatively quiet during most stages of sleep, but it becomes active during REM sleep. REM sleep is a stage where the brain dreams and reorganizes information. During this stage, the brain clears out irrelevant information by connecting experiences from the past 24 hours with previous experiences to enhance memory and promote learning and neural growth. At this point, body temperature rises, blood pressure rises, and heart rate increases. Usually, REM sleep occurs three to five times per night and does not last long.
It is not an exaggeration to say that without slow-wave sleep and REM sleep stages are enough to cause death. Long-term lack of sleep will prevent the body from repairing itself, weaken the immune system, and make the brain dull. For more information on how lack of sleep can lead to death, please read our other article "How Lack of Sleep Can Kill You."
In summary: slow-wave sleep helps you recover physically while REM sleep helps you recover mentally. These stages of sleep shorten with age, which means that sleep quality and self-repair ability also decline.
According to data from the above chart showing age-related changes in sleep patterns:
People aged 80 years spend 62% less time in slow-wave sleep than those aged 20 years on average. There are many reasons that affect cell aging and tissue aging; lack of slow-wave sleep makes it difficult for the body to repair itself and accelerates aging processes. Therefore, good sleep is the best anti-aging method.
Human Circadian Rhythm
Your sleep-wake cycle is governed by your circadian rhythm (biological clock). The circadian rhythm refers to any biological cycle variation in any organism with a 24-hour period.
The following are several key points representative of a 24-hour period:
6 A.M.: Cortisol levels rise to wake up our brains and bodies.
7 A.M.: Melatonin stops being produced.
9 A.M.: Sex hormone peaks.
10 A.M.: Mental state is optimal.
2:30 P.M.: Coordination is optimal.
3:30 P.M.: Reaction time is fastest.
5 P.M.: Cardiovascular function and muscle strength are optimal.
7 P.M.: Blood pressure and body temperature are highest.
9 P.M.: Melatonin production prepares the body for sleep.
10 P.M.: The body calms down; intestinal movement is inhibited.
2 A.M.: Deep sleep.
4 A.M.: Body temperature is lowest.
These times are not very precise but rather represent general patterns of circadian rhythm. The timing of circadian rhythms changes depending on your daily habits and other factors that affect your circadian rhythm: light exposure (light), time, and melatonin.
Light: Light may be the most significant factor affecting circadian rhythm. Staring at strong light for about 30 minutes usually resets your circadian rhythm regardless of time. When sunlight shines on your eyes as soon as it rises, it triggers a transition from one circadian rhythm to another.
Time: Your daily routine and how you complete your work will affect your sleep-wake cycle.
Melatonin: Melatonin is a hormone that induces drowsiness and controls body temperature. Melatonin production follows a regular pattern: it increases when it gets dark and decreases when dawn breaks.
How to Get Better Sleep
Now that we know how sleep works let's talk about how to get better sleep.
Avoid caffeine: If you have trouble falling asleep, removing caffeine from your diet is an effective method. Caffeine stimulates the central nervous system and severely affects most people's sleep. People who are sensitive to caffeine should stop consuming it from afternoon onwards.
Quit smoking: Smoking causes many health problems; poor quality of sleep is one of them. Studies have found that smokers get less sleep than non-smokers and have poorer quality of sleep too. If you smoke and have trouble sleeping, you may have another reason to quit smoking.
Bedroom only for sleeping and sex: Does bedroom design help with sleeping? Yes! The ideal sleeping environment should be dark, cool, and quiet. Do not turn your bedroom into a multi-purpose room. Televisions, laptops, electronic devices should be removed from your bedroom along with clutter too. When you walk into your bedroom, you should only think about sleeping there.
Sleep aids
Exercise: Exercise makes it easier for your brain and body to enter a state of rest at night. In addition, obesity also severely disrupts your sleeping patterns. As you get older exercise becomes even more important. Robust middle-aged people have significantly better quality of sleep than overweight people their age. Note that you should avoid exercising two to three hours before bedtime because adrenaline secreted after exercise makes people excited; wait until hormone levels return to normal before going to bed again.
Temperature: Cool rooms are best for sleeping quality. The ideal sleeping temperature is between 18-21 degrees Celsius.
Sound: A quiet space is key to good quality of sleep. If you cannot maintain a quiet environment around you while sleeping then try turning on fans or creating "white noise" to mask other annoying sounds around you or use earplugs instead.
Alcohol: Drinking before bed does help induce drowsiness but at the same time also reduces quality of REM sleep cycles too. This is why drinking alcohol can make you fall asleep easily but still feel tired after waking up next morning.
Falling asleep
Maintain regular routines: Our bodies like routines because circadian rhythms are our biggest daily work; so try to maintain consistent times for sleeping and waking up every day as much as possible.
Pre-sleep "shutdown" ceremony: Illuminated electronic devices will hinder melatonin production; this means that your body will lack drowsiness hormones needed for entering into deep slumber mode when sleeping at nightfall time or later on into evening time too. To be precise blue light emitted by electronic devices reduces melatonin production too. Pre-sleep "shutdown" ceremonies one or two hours before bedtime can be very helpful for sleeping quality too. In addition, working late at night makes your brain tense and prevents your body from calming down before falling asleep; as we mentioned in our previous article "How Your Brain Helps You Learn New Skills," writing before bed can help with both sleeping quality as well as learning new knowledge too!
Use relaxation techniques: Researchers believe that at least 50% of insomnia is related to emotions or stress. Finding suitable stress-relieving methods can help improve your quality of sleep too. Effective methods include writing journals/diaries/blogs/articles/posts/etc., deep breathing exercises, meditation practices or exercises too!
How to Get More Energy in the Morning
Drink a large glass of water in the morning: Your body hasn't had water all night long; if you wake up feeling sluggish in the morning then it might be due to mild dehydration too! My first thing every morning is drinking a large glass of cold water too!
Take a shower in the morning sun: Sunlight is a "new coffee." Bathing in morning sunlight is key to establishing circadian rhythms and awakening your brain too!
In Conclusion
Sleep takes up one-third of our lives but we rarely think about it seriously enough! We are obsessed with productivity culture but underestimate the importance of sleeping well too! Now is the time to develop good sleeping habits because your life depends on it!
