Sunrise and sunset, the law of life and interest has never changed since ancient times. However, "interest" is how much time, there is no rule to follow? In recent years, "Golden Rules" about how much sleep a person needs every day is endless.
Newborn, infant, adolescent and adult sleep time is obviously different. You can never ask an adult to have a newborn's sleep time. The duration of sleep varies among people of different ages, and the daily sleep duration is not exactly the same for the same age group. Someone still sleeps 8 hours a day and sleeps awkwardly, but when someone sleeps six hours a day, they can be active all day long.
In 2002, Daniel F. Kripke of the University of California, San Diego, conducted a cancer research project involving 1.1 million people over a six-year period. Statistics show that the daily sleep duration in humans ranges from 6.5 to 7.4 hours, The participants in this category had the lowest rates of death above and below this, with an increase in mortality rates, the findings of which appeared in the Archives of General Psychiatry. In 2007, Jane Ferrie, a faculty member in the Department of Epidemiology and Public Health, University College London, UK, validated the seven-hour sleep mechanism for a study of 10,308 British government employees aged 35 to 55 over 17 years. In 2014, Shawn Youngstedt, professor at the School of Nursing and Medical Innovation at Arizona State University in Phoenix, proposed the 7-hour sleep mechanism again. He believes that 7-hour sleep is the best. Sleep is harmful for 8 hours or more but less than Six hours of sleep is also harmful.
Whether human sleep time is fixed or changed with the evolution of human beings? A study by Jerome Siegel, a neuroscientist at the University of California Los Angeles (UCLA), uncovered the mystery. In 2015, Siegel said in Current Biology that hunting communities in Africa and South America sleep an average of 6.9 to 8.5 hours a day, with little rest during the day and no better sleep than those living in a modern country More. They also surveyed ethnic groups living in remote areas of Bolivia, Tanzania and South Africa and found that the sleeping habits and sleeping durations of these populations were very similar. In this study, Siegel also overthrows the folk argument that "human ancestry is longer than we sleep" by studying the sleep mechanisms of ethnic groups in pre-industrialized societies in South America and Africa. The article also contradicts the 8-hour sleep mechanism every day: adults do not need up to 8 hours of sleep per day, except for those who need increased sleep to promote brain growth.
A growing body of research data seems to favor a 7-hour sleep mechanism, and its presentation challenges the 8-hour sleep mechanism and the 4 to 5-hour sleep mechanism, which has caused considerable controversy in academia.
However, there is no absolute law, any kind of law can not cover all groups, some people sleep time is indeed lower than the reference given by all parties, it is said that Thatcher and Leonardo da Vinci sleep only 4 hours a day, there are People claim that they sleep only six hours a day, you can be full of energy all day long. So sleep time varies from person to person, and "different" from where, it is the focus of current scientists.