A recent study from Massachusetts General Hospital (MGH), published in the journal Nature, shows how getting enough sleep protects against heart disease. Insufficient sleep increases the production of inflammatory white blood cells that are known to be major contributors of atherosclerosis – the deposition of plaques of fatty material on the inner walls of arteries. Sleep helps to regulate the production in the bone marrow of these inflammatory cells. Sleep disruption breaks down the control of inflammatory cell production, leading to more inflammation and more heart disease. According to Filip Swirski, Ph.D. of the MGH Center for Systems Biology, there is a brain hormone known to control wakefulness that controls processes in the bone marrow that protects against heart disease.
Mice that had been genetically programmed to develop atherosclerosis were subjected to repeated interruptions of their sleep, similar to the experience of someone constantly waking up because of noise or discomfort. Compared to mice from the same strain that were allowed to sleep normally, those subject to sleep disruption developed larger arterial plaques and had higher levels of inflammatory cells in their blood vessels. They had a nearly two fold increase in the production of in their bone marrow of stem cells that give rise to white blood cells. A hormone called hypocretin, produced in the brain structure known as the hypothalamus, which is known to regulate sleep, was found to have an unexpected role in controlling white blood cell production. While normally produced in high levels when animals, including humans, are awake, hypocretin levels were significantly reduced in the sleep deprived mice. Dr. Swirski, an associate professor of Radiology at Harvard Medical School, plans to explore further mechanisms by which proper sleep maintains vascular health, and further explore this newly identified neuro-immune axis.
The complete article from which this column is based can be found at Science Daily, February 13, 2019.
The take home messages from this study are important. Safeguard your sleep by reducing or eliminating caffeine from coffee, caffeinated teas, caffeine containing soft drinks, kombucha, etc. late in the day. People who are sensitive to caffeine should not drink it after noon. Be careful with alcohol around bedtime as well – it can put you to sleep, but will often disrupt your sleep quality later in the night. If you have sleep apnea, take steps to control it. Sleep apnea is a serious sleep disorder - breathing is interrupted many times each night, resulting in insufficient oxygen for the brain and body. Talk to your doctor about getting a device called CPAP (continuous positive airway pressure) or talk to your dentist about a dental device that may help with sleep apnea. Losing weight may help, and so will quitting smoking! Wear blue blocking glasses starting an hour before bedtime, so that bright lights from your home, your TV, computer or cell phone will not reduce your natural melatonin production as bedtime gets near. If you get up at night to go to the bathroom, wear the blue blocking glasses at that time. All these measures are important, and potentially life saving.
Sadja Greenwood, MD, MPH
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