In modern society, it is customary to sacrifice sleep: first for the sake of kindergarten, then school, institute and, ultimately, work. In 2015, University of Oxford professor Paul Kelly, speaking at a festival of British science, equated the working day from 09:00 to 17:00 with torture, calling early waking up the most common form of civilized torture. Lack of sleep makes people more obedient, they think worse, feel lethargic and easier to manage, but a complete lack of sleep kills, but scientists do not know the exact reason. Moreover, prolonged wakefulness kills both humans and animals. A new study on fruit flies has shown that when fruit flies die of insomnia, the fatal shifts do not occur in the brain, but in the intestines.
Why is lack of sleep killing?
The first signs of sleep deprivation are well known to everyone: fatigue, difficulty concentrating, possibly irritability, or even a tired giggle. Fewer people have experienced the effects of prolonged sleep deprivation, including disorientation, paranoia, and hallucinations. However, total, prolonged sleep deprivation can lead to death. Moreover, while we are joking about this, a widely cited study on rats, conducted in 1989 by scientists from the University of Chicago, showed that a complete lack of sleep inevitably leads to death. But despite decades of research, the big question remains unanswered: Why do animals die when they are awake?
Neuroscientists at Harvard Medical School (HMS) have identified an unexpected causal link between sleep deprivation and premature death. In a study on sleep-deprived fruit flies published in the journal Cell on June 4, 2020, scientists found that death is always preceded by an accumulation of molecules known as reactive oxygen species (ROS) in the intestines.
When fruit flies were given antioxidant compounds that neutralize and remove ROS from the intestine, the sleep deprived flies remained active and had a normal lifespan. Additional experiments in mice have confirmed that ROS accumulates in the intestines when sleep is deprived. These results suggest that animals can actually survive without sleep under certain circumstances. Moreover, the work will open up new avenues of research to fully understand the effects of sleep deprivation.
Chronic sleep deprivation is fraught with the development of serious diseases
As lead author of the study, Dragan Rogul, told the News Harvard Gazette, the team took an unbiased approach and looked all over the body for signs of damage from lack of sleep. Scientists were surprised to find that the gut plays a key role in causing death. But even more surprising was the fact that premature death can be prevented.
Scientists have been studying sleep for a long time - a fundamental, in many ways mysterious phenomenon. Almost every living creature known to science sleeps or exhibits some form of sleepless behavior, and lack of sleep is fraught with serious consequences. Numerous studies have found links between regular sleep deprivation and heart disease, type 2 diabetes, cancer, obesity, depression, and many other conditions. The results also showed that prolonged, complete sleep deprivation can lead to premature death in animals. Attempts to find out what is the driver of death due to sleep deprivation, the attention of scientists was riveted to the brain, where sleep originates, but to no avail.
What's going on in the intestines?
In their study, the researchers found that sleep-deprived fruit flies died at the same rate each time. By studying markers of cell damage and death, the only tissue that was actually secreted was the gut. The team also investigated whether ROS accumulation occurs in other animal species. Compared to laboratory mice with a normal sleep / wake schedule, mice that were sleep deprived for five days had increased ROS levels in the small and large intestines. There were no changes in other organs, as in fruit flies.
Fruit flies are the real heroes of scientific research
To find out if ROS in the gut is the cause of sleep deprivation-related death, the researchers decided to determine if preventing ROS accumulation could prolong life. After testing dozens of compounds with antioxidant properties that neutralize ROS, the authors of the work identified 11 compounds, the intake of which (as a dietary supplement) allowed sleep-deprived flies to have a normal or near-normal life span. Compounds such as melatonin and lipoic acid have been shown to be particularly effective in clearing ROS from the intestine. Interestingly, the supplements did not increase the lifespan of non-sleep deprivation flies.
Thus, intestinal ROS accumulation plays a central role in sleep-related premature death, but many questions remain unanswered. So, the reason why sleep loss causes accumulation of ROS in the intestines and why this is fatally unknown. Sleep deprivation can affect the gut directly, but the trigger can also occur in the brain. Likewise, death can result from damage to the intestines, or because high levels of ROS have a systemic effect on the body, or both.