According to the Huffington Post on February 15, although it is difficult to say what sleep is "just right", most adults only need seven to nine hours of sleep every night to achieve the best sensory and physical performance.
If adults often sleep more than nine hours a night, it will affect their health. Here are 8 big risks to the body caused by too much sleep.
1. Increase the risk of diabetes
In a small study in Quebec, Canada, people who sleep more than eight hours a night for six years are twice as likely to develop type 2 diabetes (or sugar tolerance) as people who sleep only seven to eight hours a night.
2. Cause weight gain
In the study, the researchers also looked at weight and fat gain in Quebec adults over a six-year period. They found that people who sleep too short and too long every night gain more weight than those who sleep seven or eight hours.
During the study, people who slept 9 to 10 hours a night were 25% more likely to gain 5 kg, even if they controlled food intake and increased physical activity. As a result, these results highlight the need to consider sleep time as a factor in weight gain and obesity, the researchers wrote in the study.
3. Increase the risk of depression
According to a 2014 study of adult twins, researchers found that long sleep increased the risk of depression. In this study, participants who slept only seven to nine hours a night were 27 percent more likely to have depression, while those who slept more than nine hours were 49 percent more likely to have depression.
4. Brain damage
A 2012 study found that older women who sleep too much (or too little) lose their brain function over six years. According to the Huffington Post at the time, women who sleep more than nine hours (or less than five hours) a night will age their brains for two years.
5. It may be more difficult to conceive
In 2013, a South Korean team analyzed the sleep habits of more than 650 IVF women. The study found that the highest pregnancy rate was among women who slept seven or eight hours a night, while the lowest was among women who slept nine to 11 hours.
However, the result does not establish a clear causal relationship Dr. Evan Rosenbluth, a reproductive endocrinologist, told the Huffington Post: 'we know that sleep habits definitely change circadian rhythms, hormone secretion and menstrual cycles. However, the impact on infertility is a little difficult to understand, because there are so many details that are difficult to control. '
6. Heart injury
In 2012, a study at the American College of Cardiology conference showed that sleeping more than eight hours a night increased the risk of heart disease. The researchers analyzed data from more than 3000 people and found that people who slept long had twice the risk of angina and 1.1 times the risk of coronary artery disease.
7. Early death
In 2010, in an analysis of 16 different studies, researchers found that regardless of the cause, people who slept too long and too short had an increased risk of death.
After analyzing 16 studies involving more than 1.3 million people, a team from the University of Warwick in the UK and the school of medicine at the University of Federico II in Naples found that people who sleep more than eight hours a night are 1.3 times more likely to die.