A new study published in the European Heart Journal has concluded that both excessive and insufficient sleep increases the risk of heart problems and the chances of premature death.
The study conducted by Chuangshi Wang from McMaster University, Ontario, Canada, and his team of researchers, included data from more than 116,000 people between the ages of 35 and 70 from 27 different countries. Participants were all enrolled in the Urban Rural Epidemiology Prospective (PURE) observational study. The researchers used variables including: socioeconomic status, lifestyle habits, physical activity, diet, use of various medications and family history of chronic conditions to make a comprehensive analysis of sleep habits.
[The consequences of not getting enough sleep
photo gallery: 1. BMI, 2. Blood pressure, 3. Stomach, 4. Pancreas, 5. Reflexes, 6. Brain]
After an average follow-up period of nearly eight years, researchers recorded 4,381 deaths and 4,365 heart attacks or strokes from participants.
Wang's analysis revealed that people who regularly had more than the recommended maximum of 8 hours of sleep per night, had a much higher chance of dying prematurely or developing heart disease.
Specifically, the risk of premature death or cardiovascular conditions was 5% higher for people who slept 8 to 9 hours per night than for people who slept the recommended 6 to 8 hours.
Those who on average slept for 9 to 10 hours per night, were 17% more at risk and those who slept regularly for more than 10 hours were 41% more likely to die prematurely or develop cardiovascular problems.
The study also found that people who slept 6 hours or less, were 9% more at risk of cardiovascular problems.
Leader researcher Wang said: "Our study shows that the estimated optimal sleep duration is six to eight hours per day for adults.”
"Since this is an observational study that can only show an association instead of demonstrating a causal relationship, we can not actively say that this study proves that too much sleep per se causes cardiovascular diseases.
"However, sleeping too little could be an underlying factor in death and cases of cardiovascular disease. Also, sleeping too much can indicate underlying conditions that increase the risk.”
Co-author Professor Salim Yusuf, also from McMaster University, Ontario, Canada added: "The general public should make sure that they sleep approximately six to eight hours a day.
“On the other hand, if you sleep too much regularly, let’s say more than nine hours a day, you may want to visit a doctor to check your overall health.