Sleep Is the Most Productive Part of the Day.
The hours spent sleeping are especially critical for yourÂ brain
Sleep, you have heard, is essential for human health and development. Newborns and toddlers tend to spend more than half of every day asleep. And while many adults try to get by with less, most people need between seven and nine hours each night in order to perform and feel their best.
While thereâ€™s no doubt that sleep is necessary, thereâ€™s still a lot about it that befuddles sleep experts. â€œDespite years of scientific research and studies, we still donâ€™t completely understand why we need to sleep,â€ says says Dr. Leila Kheirandish-Gozal, a sleep research and professor of pediatrics at the University of Missouri School of Medicine. â€œWe also still donâ€™t know why we dream.â€
What experts do know is that sleep is a surprisingly active and fertile time for the brain. Sleep seems to play a crucial role in helping your brain sort, process, store, and make use of the stuff you encounter during your waking hours.
â€œSome people think of it as a waste of timeâ€Šâ€”â€Šas turning the brain off,â€ says Dr. Carl Bazil, director of the Division of Epilepsy and Sleep at the Columbia University College of Physicians and Surgeons. â€œBut we know now thereâ€™s a lot of brain activity going on, and all different types of activity depending on the stage of sleep youâ€™re in.â€
Bazil says a pile of research has established that sleep helps people turn short-term memories into durable, long-term ones. And sleep also helps your brain sift out and dispose of the jetsam thatâ€™s not worth holding onto,Â more research suggests.
Sleep also appears to assist the brain with meaning-making and other complex aspects of learning. For example,Â evidence shows that sleep strengthens â€œrelational memory,â€ which is a kind of logical, inference-based intelligence that allows people to put two and two together in order to make good decisions.
Sleep may also play a role in motor-task learning. Musicians, dancers, and athletes often find that, following a good nightâ€™s sleep, theyâ€™re much better at a new skill than they were the day before when they quit practising, Bazil says.
While your brain is able to engage in some of these chores while youâ€™re awake, the hours you spend asleep seem to do all this more thoroughly and efficiently.
â€œThe overriding theme is that your brain canâ€™t constantly be bombarded with information and be expected to process it,â€ Bazil says. In many ways, itâ€™s accurate to think of your waking hours as the data-collection phase of your day, while the hours you spend asleep are the time when your brain sorts and makes use of that information.Â Skimp on sleep, and you handicap your brainâ€™s processing power.
But these cognitive duties are a mere snapshot of sleepâ€™s panoramic range of responsibilities.
â€œSleep is an evolutionary function that seems to be extremely important for our health and survival,â€ says Kheirandish-Gozal.
She says mood is regulated by sleep, and that a lack of quality rest can result in irritability, depression, anxiety, and behavioral changes. Thereâ€™s also evidence that metabolic waste is cleared out of your brain and body while you sleep, and that sleep promotes cellular repair and recovery.
This waste-removing function may be especially critical when it comes to a personâ€™s risk for disease. SomeÂ high-quality research in miceÂ has shown that cerebral spinal fluid, which flows through the brain and removes accumulated proteins and other detritus, all but trickles when mice are awake. But its flow surges during sleep. Protein accumulation is one hallmark of Alzheimerâ€™s disease, and so the protein-clearing function of sleep may play a part in the diseaseâ€™s development.