There are still many mysteries remained about the sleep mechanism; however, there is no doubt that maintaining a sound biological rhythm is the foundation of health
Most of us have had such an experience: we painstakingly burn the midnight oil, yet at the end we don’t really remember many things from what we’re reading. Moreover, we feel so sleepy the next day and become retarded in reacting. The less we sleep, the easier we lose our temper. In fact, lack of sleep will not only affects our memory and mental health, but also directly harms our immune system. Researchers who did an experiment among young people found that if they sleep for only 4 hours or less, even for just one night, they will suffer loss of certain anti-cancer immune cells by 70% the following day.
However, it may be you have some friends who sleep less than you but are as energetic as you are. You need eight hours sleep while they need only 5-6 hours.
Scientists early on discovered that gene mutation is responsible for innate sleeplessness. Insomnia can also be related to to genes. In recent research on sleep, fruit flies helped researchers arrive at a conclusion on how long one needs to sleep is a result of multiplied gene regulation.
Your internal clock and your chronotype
According to the U.S. National Sleep Foundation, about 47 million adults fail to have sufficient sleep. Every year, occupational injury and productivity reduction due to lack of sleep causes losses of US$1.8 billion. About 1.2 million traffic accidents, 1/5 of the total, result from fatigued driving. The cost of lack of sleep is thousands of lives.
But there are so many mysteries still remaining about the sleep mechanism. It is so important to study it. It explains why the Nobel Prize in Physiology or Medicine was given to the scientists, Jeffery C. Hall, Michael Rosbash and Michael W. Young, who revealed the secrets that regulate people’s internal clocks.
The internal clock, or circadian rhythms, exists in every cell and organ of the body. The suprachiasmatic nucleus (SCN), which is located in the front of the hypothalamus and on the upper optic chiasma, is the significant biology center to regulate the rhythm of different vital activities of the body, from eating and sleeping to hormone secretion. When light rays fall on the retina, neural signals are sent to the SCN – “now it’s daytime”. SCN then begins to adjust the multiple internal clocks to work synchronously within the body according to the outward environment, and to the clues indicating the shift in day and night.
But it varies from individual to individual how their bodies react to the clues delivered by light rays. Scientists have created a special term “chronotype” to better explain the early bird and late bird syndrome. The early bird has “early” chronotype. They begin their physiological activities once the sun comes up or even before dawn. But those of “late” chronotype will sleep one more hour even though they have received the sun ray signal at the same time as the early bird. We may also have already noticed that our chronotype undergo changes with age. In our childhood, we wake up and get up early. In adolescence, it’s hard for us to get up on time. And when we become adults, it then becomes easier and easier for us to get up early.
Chronotype is affected by gene
Researchers asked the testees to record their sleep mode during the days when they don’t need to go to work or school. Most people sleep at 11 pm and get up at 7 am. This is an average chronotype. People of “late” chronotype say that when they have to get up early in week days, they feel as painful as flying over several time zones.
To people of average chronotype, their SCN begins to order the body to secrete melatonin, a sleep hormone at 9 pm. That’s the time when they start to feel sleepy and their gastrointestinal motility turns slows down. At about 10:30 pm, their body temperature falls and gets ready to sleep. Then at 6:30 next morning, with the regulation of SCN, blood pressure elevates and the body is awakened. At 10 am, people’s mental alertness reaches its peak.
But to people of “late” chronotype, all these physiological activities begin later and they are unable to change it. Some studies show that the fixed working hours of society give much pressure to these late birds and so they are more likely to become smokers or even suffer depression.
“To maintain sound biological rhythms is the foundation of health,” said Emily, a post-doctor at Salk Institute for Biological Studies, who studies human circadian rhythms. “We focus on how we eat and exercise and how long we have slept, yet when to sleep is also a significant aspect to keep health.”
The reason why people have different chronotype is that their “clock gene” in the brain cells at SCN are activated and stopped at different times of the day. The protein amount generated thus forms a fluctuating line. Like signals, these protein regulate various physiological activities. After studying on families whose entire members all get up early, scientists discovered that these members carry the same gene mutation of “clock gene”. In other words, to some extent, it is a genetic matter whether you get up/sleep early or late.
Fruit flies give the answer
Which genes are accounted for? In mid-December last year, scientists from the Heart, Lung and Blood Institute of the U.S. National Institute of Health issued their latest discoveries concerning sleep time on PLoS Genetics. They had mated fruit flies who both slept a long time with those who both slept a short time. Then from their descendants 13 generations later, the researchers selected two groups of fruit flies. One group slept 700 minutes every day while the other slept 100 minutes every day.
Afterwards, researchers carried out a comprehensive comparison between the two groups and discovered there are 126 obvious differences in 80 genes. Many of these genes relevant to sleep time are part of important cytobiology channels such as those deciding brain development, memory and study capacity.
Susan Harbinson is one of the authors of the article. She says: “We didn’t use transgenic fruit flies or genetic engineering methods as many other laboratories do. We only used the natural gene to create fruit flies that sleep a long time or short time.” Harbinson also says that before the research, they are not sure whether such extreme sleep patterns exist in natural fruit flies.
Another interesting discovery is that Harbinson’s fruit flies who have extreme sleep time enjoy a longevity similar to ordinary wild fruit flies. It indicates that these fruit flies don’t have physiological defect. Perhaps, as long as the individual can get enough sleep itself needs, it doesn’t matter at all if the amount is far from the average. At least, if you were a fruit fly, this inference is true.
If the same findings are true among humans, then scientists will hopefully carve out new ways to solve more healthy problems related to sleep such as insomnia and narcolepsy, as well as unfolding the mysteries of the sleep mechanism.
How to sleep better
You may be envious of your friends who don’t need much sleep. However, no matter which chronotype you are and how long you need to sleep, there are scientific ways to follow in order to improve your sleep quality so you can really “sleep like a baby”.
Matthew P. Walker, the director at the Center for Human Sleep in Berkeley, California offers practical suggestions in his article published in New Scientist.
- Regularity. No matter what happens, try to sleep and get up at regular time periods every day, even if you don’t sleep well the day before or you don’t have to get up for work during the weekends. The time to get up is an important factor because it will decide your sleep drive during the day. The impulse to sleep is a significant part of the internal clock operation.
- Temperature. Turn down the air-conditioner or heater because you need to lower your body temperature by 1.2 degrees centigrade to be ready for sleep. That’s why people more often doze in cool places instead of hot. 18.5 degrees centigrade is the most ideal temperature for the bedroom. If you are one of those people with cold feet, you can put on socks while sleeping, but the whole room should be kept in a fairly low temperature.
- Light rays. Dim light is the best friend of sleep. Turn off lamp sources as many as possible one hour before you sleep so that your melatonin (which is secreted only in the evening) can work soundly. Pads and mobile phones will particularly send out short wave blue rays which will reduce the melatonin density in the body. Therefore, if you want to sleep better, turn off all these screens one hour before sleep. Curtains that completely keep out outward light rays will also help.
- Take a walk. Never lie on the bed for more than 20 minutes. If you fail to fall asleep, get up to take some walk or do some relaxing things until the “sleep drive” gets back to you.
- Say goodbye to coffee. It’s also nonsense that alcohol can facilitate sleep. If you want to have good sleep quality, don’t drink coffee after 1 pm and flee away from alcohol after 5 or 6 pm. Don’t go to the bed drunk. It is true that alcohol has a calming effect, but a calm statement is a totally different concept from sleep. On the contrary, alcohol will hinder normal REM sleep and completely destroy this important sleep phase. That’s why if you drink alcohol the evening before, you will get up feeling fatigued.
To spas, before treatments, they can firstly ask about the sleep condition of the guests. For guests with high sleep quality and full of energy, no matter how long they sleep, every treatment will bring forth good effects on them. If the guests are not satisfied with their sleep quality or time length, then the treatments to recommend are surely those to facilitate sleep and help relaxation. Many guests say that they fall deep sleep during the treatment, and this is the best result.