Heart diseases are among the leading cause of death in both men and women. Scientists found that the disruption in the sleep cycle of the mouse leads to low level of hypocretin in the body. It is a hormone that regulates the sleep and wake cycles. This research suggests that a decline in the level of hypocretin leads to inflammation and fat buildup in mouse arteries.
Researchers at Harvard Medical School and Massachusetts General Hospital conducted this research. NIH’s National Heart, Lung and Blood Institute in part supports this research. Swiss National Science Foundation, Government of Canada, Austrian Science Fund, German Research Foundation, and Boehringer-Ingelheim-Fonds also funds this research. The study appears in Nature.
What did the Researchers do?
When fatty deposits called plaque build inside the blood vessels, it is called atherosclerosis. White blood cells deposit on the site of plaque and cause inflammation. With the passage of time, plaque increases in size and narrows the blood vessels particularly arteries. It limits the oxygen flow to tissues and organs of the body. Consequently, it leads to heart attack, stroke and even death.
Researchers have linked sleep disorders directly to cardiovascular problems. But the mechanism that links them is unclear. To better understand it, scientists studied a mice group modified genetically to develop atherosclerosis at some point. Researchers on purpose disrupted sleep cycle of half of the mice. However, the other half followed a normal sleeping pattern. After sixteen weeks, sleep disturbed mice had larger plaque formation inside their arteries. Mice with normal sleep had less plaque formation.
What did they find?
Mice with abnormal sleep cycle also had high amounts of WBCs in blood. In addition to that, they had low levels of hypocretin (brain hormone that regulates sleep). Further evaluation depicted that hypocretin suppresses the stem cells that produce WBCs in bone marrow. In this way, it controls the production of white blood cells
Moreover, scientists gave hypocretin supplements to some mice. These mice produced less white blood cells than the mice without supplementation. These mice also developed smaller plaque than the other mice. This research clearly suggests that abnormal sleep cycle leads to low levels of hypocretin. Declining levels of hypocretin are directly related to inflammation in arteries by WBCS and atherosclerosis.
How is this research helpful?
Scientists have developed a technique that induces the brain to produce a hormone that controls the production of inflammatory cells. It controls in a way that blood vessels are protected from lethal damage. Sleep and wake cycle regulates this mechanism. It is distorted when there is any disruption in the sleep cycle. Till today, this mechanism is the most direct method that connects sleep to heart diseases.
If humans also experience the same effects due to sleep disruption, this research will appear very helpful. It will form new horizons to develop ways for the treatment of heart diseases.