The two most feared diseases throughout developed nations are dementia and cancer. Both are related to inadequate sleep.
A lack of sleep is fast becoming recognized as a key lifestyle factor determining whether or not you will develop Alzheimer’s disease. The condition, originally identified in 1901 by German physician Dr. Aloysius Alzheimer, has become one of the largest public health and economic challenges of the twenty-first century.
More than 40 million people suffer from the debilitating disease. That number has accelerated as the human life span has stretched, but also, importantly, as total sleep time has decreased.
One in ten adults over the age of sixty-five now suffers from Alzheimer’s disease. Without advances in diagnosis, prevention, and therapeutics, the escalation will continue.
Sleep represents a new candidate for hope on all three of these fronts: diagnosis, prevention, and therapeutics. Before discussing why, let me first describe how sleep disruption and Alzheimer’s disease are causally linked.
Sleep quality, especially that of deep NREM sleep—deteriorates as we age. This is linked to a decline in memory. However, if you assess a patient with Alzheimer’s disease, the disruption of deep sleep is far more exaggerated. More telling, perhaps, is the fact that sleep disturbance precedes the onset of Alzheimer’s disease by several years, suggesting that it may be an early-warning sign of the condition, or even a contributor to it.
Following diagnosis, the magnitude of sleep disruption will then progress in unison with the symptom severity of the Alzheimer’s patient, further suggesting a link between the two.
Making matters worse, over 60 percent of patients with Alzheimer’s disease have at least one clinical sleep disorder. Insomnia is especially common, as caregivers of a loved one with Alzheimer’s disease will know all too well. It was not until relatively recently, however, that the association between disturbed sleep and Alzheimer’s disease was realized to be more than just an association.
While much remains to be understood, we now recognize that sleep disruption and Alzheimer’s disease interact in a self-fulfilling, negative spiral that can initiate and/or accelerate the condition.
Alzheimer’s disease is associated with the buildup of a toxic form of protein called beta-amyloid, which aggregates in sticky clumps, or plaques, within the brain.
Amyloid plaques are poisonous to neurons, killing the surrounding brain cells. What is strange, however, is that amyloid plaques only affect some parts of the brain and not others, the reasons for which remain unclear.
Amyloid accumulates in the middle part of the frontal lobe, which, is the same brain region essential for the electrical generation of deep NREM sleep in healthy young individuals.
Getting too little sleep across the adult life span will significantly raise your risk of developing Alzheimer’s disease.
This relationship has now been reported in numerous epidemiological studies, including those individuals suffering from sleep disorders such as insomnia and sleep apnea.
Insufficient sleep is only one among several risk factors associated with Alzheimer’s disease. Sleep alone will not be the magic bullet that eradicates dementia. Nevertheless, prioritizing sleep across the life span is clearly becoming a significant factor for lowering Alzheimer’s disease risk.