UCLA and Harvard-Trained Cardiologist Explains Why Sleep Is Crucial for Brain Health

New Delhi | September 17, 2025

How much sleep do you really need? While most studies recommend seven to nine hours of quality rest each night, the answer is not the same for everyone. Factors like age, gender, job stress, and lifestyle all shape individual sleep needs. But one thing remains clear—sleep is not just downtime for the body. According to UCLA- and Harvard-trained cardiologist Dr. Hafiza Khan, sleep is when the brain undergoes its most remarkable process of restoration. Why Sleep Matters More Than We Think To emphasize the significance of rest, Dr. Khan shared insights from a groundbreaking 2019 Boston University study that revealed what happens inside the brain during sleep. The research, led by Professor Laura Lewis, produced the first-ever images of cerebrospinal fluid actively washing in and out of the brain while a person sleeps. Dr. Khan explained that this rhythmic process is vital for maintaining brain health. “Sleep is an active process by which our brain (and heart) restores, repairs, and resets for the day ahead,” she said, highlighting why inadequate rest can compromise both neurological and cardiovascular health. The Brain’s Nightly “Cleaning Service” According to the Boston University study, the sleeping brain shows a fascinating sequence of events. First, neurons quiet down. Then, blood briefly flows out of the brain, making room for cerebrospinal fluid (CSF)—a clear, watery liquid that pulses through brain tissue in waves. “These waves wash through your brain, clearing away toxins and refreshing neural pathways,” Dr. Khan noted. “It’s almost like your brain is giving itself a nightly cleanse.” The research used advanced imaging techniques to capture red waves of blood oxygenation followed by blue waves of CSF circulation, providing a visual explanation of why deep sleep is restorative. Beyond Rest: Repair and Reset Dr. Khan stressed that sleep is not just about resting tired muscles or recharging mental focus—it’s about biological repair at a fundamental level. While awake, the brain is busy processing information, solving problems, and responding to stimuli. During sleep, however, it switches into maintenance mode, activating mechanisms that support memory consolidation, toxin clearance, and even cardiovascular balance. This is why chronic sleep deprivation has been linked to conditions like hypertension, heart disease, diabetes, and cognitive decline. By skipping quality rest, people miss out on the very process that keeps the brain and heart resilient. Different Needs, Same Importance While every person’s optimal sleep duration may vary, the principle remains universal: sufficient sleep is essential for long-term health. Dr. Khan urged people to prioritize rest just as much as diet and exercise. “Everybody’s sleep needs differ, but the importance of sleep doesn’t change,” she said. A Note of Caution Dr. Khan also reminded readers that her observations are for general awareness, not a substitute for professional medical guidance. Anyone experiencing persistent sleep issues or related health problems should seek medical advice from a qualified healthcare provider. As science continues to uncover the mysteries of sleep, studies like the one at Boston University make it clear: while you sleep, your brain doesn’t switch off. It’s hard at work, washing, repairing, and preparing you for the next day.