In this episode of the NutritionFacts.org podcast, Dr. Michael Greger explores the science of sleep—its role in health, how much we really need, and what modern research reveals about its link to ageing, disease, and brain function.

Key Points:

Sleep keeps the brain and body healthy, with seven hours a night emerging as the optimal range. Beyond rest, sleep is essential for clearing toxins and lowering risks of chronic disease. 

• Melatonin and Ageing: Melatonin declines with age and is sometimes used to treat insomnia, but supplements are poorly regulated and may not be as effective—or safe—as often advertised. Some foods and nutrients like magnesium may naturally boost melatonin levels.
• Optimal Sleep Duration: Large-scale studies suggest the sweet spot is around seven hours per night. Both shorter and longer sleep are linked with higher risks of chronic disease and premature death.
• Sleep and Brain Health: Sleep plays a vital role in clearing waste products, such as beta amyloid, from the brain. Too little sleep raises the risk of cognitive decline and Alzheimer’s disease.
• Modern Sleep Patterns: Despite fears of a “sleep loss epidemic,” research shows adult sleep duration has not changed much since the 1960s. Pre-industrial societies also averaged about 6.5–7 hours, suggesting this may be natural for humans.