Although more and more studies support the idea that the quality of sleep is as important as the quantity, sleeping a minimum of hours each night is a guarantee of health and well-being. Even if you are one of those people who with five hours of sleep claim to be like a rose, the chronic lack of rest can end up taking its toll.
We present here a selection of six works that demonstrate the negative effects of sleeping less than six hours. Six reasons, one for every hour of rest, to reorganize your schedule and try to spend more time in the placid arms of Morpheus.
More cardiovascular risk
Sleeping less than six hours a day increases cardiovascular risk, a study published in the Journal of the American College of Cardiology found in early 2019. The researchers used 3D cardiac ultrasound and CT scans to detect the presence of heart conditions in the nearly 4,000 participants in the study.
“We have seen that participants who slept less than 6 hours a day or had a very fragmented and poor quality sleep had more cholesterol plaques, compared to those who slept longer hours or had a less fragmented sleep,” explained Fernando Domínguez, one of the authors of the article. “The duration and quality of sleep are of vital importance for cardiovascular health.”
Specifically, the results revealed that those who slept less than six hours were 27% more likely to suffer from atherosclerosis compared to those who enjoyed seven or eight hours of sleep . Furthermore, those who had poor quality of sleep were 34% more likely to have atherosclerosis, compared to those with good quality of sleep.
You catch more colds
People who sleep six hours or less are up to four times more likely to catch a cold compared to those who enjoy more hours of sleep. These were the conclusions of a study published in the journal Sleep in 2015.
The researchers recruited 164 volunteers who underwent various health tests to learn about their sleeping habits and to be able to control other risk variables such as stress or tobacco and alcohol consumption. In addition, in another of the tests, the participants were ‘kidnapped’ in a hotel for a week and inoculated with the cold virus, collecting daily mucus samples to see in which people the infection thrived.
“In our modern culture, many people take pride in spending a few hours sleeping and many hours working,” reflected one of the authors. “We need more studies like this to show that sleep is essential for our health and well-being.”
More likely to be dehydrated
A study published in Sleep magazine at the end of 2018 indicated that adults who only sleep six hours each night are more likely to suffer dehydration than those who rest eight hours. The results revealed that the urine of those who enjoy fewer hours of sleep was more concentrated and had a 16-59% higher risk of dehydration.
Why does this happen? The answer lies in vasopressin, a hormone that helps regulate the body’s hydration status and is produced throughout the day and night. ” Vasopressin is released more rapidly at the end of the sleep cycle ,” explained Asher Rosinger, a researcher at Penn State University (USA) and one of the authors of the work. “If you wake up earlier you would be missing that release window, which would cause an interruption in the hydration of the body.”
Vaccines are less effective
This was the conclusion of a study carried out by researchers at the University of California in San Francisco (USA) in 2012 in which they evaluated the effect of the hepatitis B vaccine in a sample of adults between 40 and 60 years old. To do this, antibody levels were measured before the second and third injection of the vaccine, and six months after the final vaccination to determine if the participants had developed a protective immune response against the virus.
The results revealed that people who slept less than six hours each night were much less likely to develop antibody responses to the vaccine and therefore 11.5 times more likely to be unprotected than those who sleep an average of more than seven hours. The quality of sleep did not affect the response to the vaccines.
Increased risk of stroke
A 2012 study by researchers at the University of Alabama (USA) revealed that, in normal-weight adult males without obstructive sleep apnea, regularly sleeping less than six hours significantly increases the risk of stroke .
“We believe that the short duration of sleep is a precursor to other risk factors for stroke,” explained Megan Ruiter, one of the authors of this study in which various variables related to the previous health of the participants were taken into account.
Lower performance during the day
It seems obvious that when you sleep less, productivity and attention span decrease throughout the day. However, it was not clear whether these performance problems were due to lack of sleep per se or to prolonged wakefulness. That is, if, for example, you have the habit of sleeping only five hours, it also implies that you will be awake for 19 hours in a row.
To resolve this issue, a team of researchers from Brigham Women’s Hospital (USA) exposed nine volunteers to a twenty-hour ‘day’ for just over a month. In this way they were able to separate the impacts of a chronic short sleep from those of a prolonged waking state.
Participants were restricted to 4.67 hours of sleep and 15.33 hours of wakefulness for each 20-hour ‘day’; this corresponds to approximately 5.5 hours of sleep in a 24-hour day. Eight healthy controls were allowed to sleep 6.67 hours and have 13.33 hours of wakefulness per 20-hour ‘day’, the equivalent of sleeping 8 hours in a 24-hour day. Since 15.33 hours of wakefulness is not considered long wakefulness, but 4.67 hours of sleep is considered short sleep, we could isolate performance deficiencies due to short sleep itself.
The results, published in the journal PNAS in 2018, revealed that people with restricted sleep had more attention problems and doubled their neurobehavioral reaction time compared to controls. They also obtained lower performances when developing cognitive tasks, which suggests that, indeed, people are not capable of adapting to chronic restricted ground, regardless of waking hours.
