NAD—short for nicotinamide adenine dinucleotide–is a molecule that performs an array of important helper functions in the body. NAD is a coenzyme, which helps enzymes function effectively. NAD plays a critical role in several cellular functions, including:

Repairing DNA

Helping cells produce energy from food

Protecting cells from stress

Facilitating gene communication

NAD plays an important role in maintaining healthy metabolic function, and protects the brain from damaging oxidative stress. Critically for sleep, NAD contributes to the regulation of circadian rhythms and sleep-wake cycles.

Our bodies produce NAD on their own. As we age, NAD levels decline. Lower levels of NAD are associated with cellular aging, as well as metabolic dysfunction and greater risks of chronic, age-related diseases including diabetes, cardiovascular disease, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s.

Potential benefits of increasing NAD levels

For sleep and circadian rhythms. There’s a complex, two-way relationship between NAD and circadian rhythms, one that influences sleep-wake patterns and other important physiological processes, including metabolism.

Like so many of our body functions, NAD activity is regulated by circadian rhythms. But in ways scientists are increasingly discovering, NAD also helps to regulate and control circadian function in the body, helping to keep daily bio rhythms on track and in sync. Among the roles that NAD plays in maintaining healthy circadian function? It helps the body’s circadian system communicate with cells, specifically about mitochondrial—or energy producing activity.

Mitochondria are the engine of our cells, the parts of cells that drive energy production, and enable cells to burn stored energy as fuel. Mitochondrial activity is governed by circadian rhythms, and when this activity isn’t working optimally, it will have broad effects across the body, including for sleep-wake cycles and metabolic health. NAD appears to provide an important communication link between our circadian systems and the mitochondria within our cells. NAD also helps maintain the proper activity of the genes that communicate circadian messages, and works to repair DNA that directs circadian function.

When NAD levels are off—too high or too low—circadian rhythms are likely to thrown off as well. Age-related decline in NAD may be one reason that circadian rhythms are less robust and in sync with age, and sleep can become more restless and less restorative. And NAD’s impact on other health systems—including metabolism, cardiovascular and brain health—can have powerful indirect effects on sleep cycles.

A quick recap on the ways NAD can benefit sleep:

NAD levels are regulated by daily bio rhythms

NAD also plays an important role in keeping circadian rhythms in sync—and with them, daily cycles of sleep

NAD helps to repair and protect the genes that drive circadian rhythms

NAD helps the circadian clock communicate with cells throughout the body

For neuroprotection. NAD is prominently involved in maintaining the health of brain cells. NAD stimulates production of a protein—PGC-1-alpha—that protects against damage to the cells of the brain. Studies in animals have shown that supplements that increase NAD elevate the production of that neuroprotective protein, and limit the production of the damaging beta-amyloid proteins associated with Alzheimer’s disease, as well as the neurological damage associated with Parkinson’s disease. Research in animals has shown increasing NAD can improve memory. We haven’t yet seen studies in humans to demonstrate what cognitive benefits can be achieved by increasing NAD with supplements, but this animal research looks promising.

For metabolic health. NAD and supplements designed to elevate this compound have attracted a great deal of attention as a nutritional therapy to treat metabolic conditions, including obesity, prediabetes and diabetes. NAD is deeply involved in energy metabolism at a cellular level, and there are links between declines in NAD and metabolic dysfunction. The role that NAD plays in maintaining healthy circadian rhythms is important to metabolic health, as well as to sleep. Metabolism is maintained by circadian rhythms—they regulate our appetite, when and how well we burn energy (aka calories), how much energy we have for exercise, how well our bodies transfer glucose from blood to cells. Studies in animals show that increasing NAD levels can improve insulin sensitivity, increase glucose tolerance, and may help make it easier to lose weight. A low metabolism encourages weight gain, which elevates our risk for obstructive sleep apnea. Keeping at a healthy weight, with healthy metabolic function, are two ways to protect sleep, especially as we age. Several clinical trials in humans are underway, which I hope will give us more information about how NAD supplementation may benefit a healthy metabolism.

For cardiovascular health. Diminishing NAD levels are a cause of vascular aging. A number of studies in animals show that supplements that increase NAD benefit the health and function of the cardiovascular system, including reducing stiffness and restoring better, more youthful functioning to arteries, reducing inflammation, and encouraging the growth of new blood vessels. Research in middle aged and older adults has shown that NAD supplements can lower blood pressure and reduce aortic stiffness, both of which elevate risk for heart attack and other age-related cardiovascular conditions. Poor sleep itself is strongly linked to vascular aging, which I wrote about in my first book, Beauty Sleep.

For physical strength and exercise capacity. There’s evidence, through research in animals, that NAD can increase stamina and physical endurance, provide more strength to muscles and also help them function better. Physical strength and the ability to exercise are critical to aging well (and more slowly) and to sleeping well as we do so.

For longevity. NAD has received a lot of attention as a nutritional tool for extending lifespan, and slowing or reversing the effects of aging. Why? For the reasons we’ve discussed here, including its role as a cell protector and buffer against cell damage, its ability to improve cell function, it’s contribution to repairing DNA, supporting healthy gene activity, and regulating circadian rhythms. In addition, research in animals has shown NAD supplements can lengthen lifespan. Studies in humans will deliver important information about how NAD supplementation may work to slow the aging process, and offer protection against age-related diseases.