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Have you ever wondered why sleep is so important ? You would have heard when you sleep it flushes out all toxins from the brain, cleans up, gives you freshness in the morning to work through the day. Well yes that's true! "Sleep is as important as food, and it's miraculous how well sleep matches the needs of our nervous system. From jellyfish to birds to whales, everyone sleeps. While we sleep, our brains are not resting"

As you know Sleep deprivation can lead to health problems in both animals and humans. Answering the importance of sleep, UCLA-led team of scientists has shown for the first time that a dramatic change in the purpose of sleep occurs at the 2 and half years of age.

Rapid eye movement (REM) sleep is a stage of sleep, where during this cycle of your sleep, your eyes will move and dart quickly beneath your eyelids. During REM sleep, your brain activity increases, your pulse quickens, and you have dreams. REM sleep first takes place after you've been sleeping for around 90 minutes. When you are 2 and half years old, the brain develops very rapidly. During REM sleep, when vivid dreams occur in infants, the young brain is busy building and strengthening synapses which are the structures that connect neurons to one another and allow them to communicate.

In their scientific report published in the journal Science Advances explains after 2 and half years the brain’s prime purpose is to switch from brain building to brain maintenance and repair, a role it maintains for the rest of our lives.

Gina Poe, a UCLA professor of integrative biology and physiology who has conducted sleep research for more than 30 years and also the senior author says, “Don't wake babies up during REM sleep, important work is being done in their brains as they sleep.”

When you are awake there is naturally a certain amount of neurological damage and the resulting debris includes damaged genes and proteins within neurons that can build up and cause brain diseases, Your sleep helps to repair then and clear all debris, decluttering and taking all the trash out and clearing your brain

Van Savage, a UCLA professor of ecology and evolutionary biology and of computational medicine, and his colleagues. Observed all brain repairs occur during sleep, "I was shocked how huge a change this is over a short period of time, and that this switch occurs when we're so young," Savage said. "It's a transition that is analogous to when water freezes to ice"

They carried out comprehensive statistical analysis of sleep to date using data from more than 60 sleep studies involving humans and other mammals. They examined data on sleep of all stages which includes total sleep time, REM sleep time, brain size and body size and then built a mathematical model and tested it to explain how sleep changes with brain and body size. The research team, which included scientists with expertise in neuroscience, biology, mathematics and statistics,

The results were surprisingly consistent that all species experienced a pronounced decline in REM sleep when they reached the human developmental equivalent of about 2-and-half years of age. The fraction of time spent in REM sleep before and after that point was roughly the same, whether the researchers studied rabbits, rats, pigs or humans.

“REM sleep decreases with the growth in brain size throughout development, the scientists found. While newborns spend about 50% of their sleep time in REM sleep, that falls to about 25% by the age of 10 and continues to decrease with age. Adults older than 50 spend approximately 15% of their time asleep in REM. The significant drop off in REM sleep at about 2-and-a-half happens just as the major change in the function of sleep occurs,” Poe


A chronic lack of sleep likely contributes to long-term health problems such as dementia and other cognitive disorders, diabetes, and obesity, to name a few, Poe said. When you start to feel tired, she said, don't fight it, go to bed.

"I fought sleep and pulled all-nighters when I was in college, and now think that was a mistake," Savage said. "I would have been better off with a good night's sleep. Now when I feel tired, I don't have any guilt about sleeping."

A regular seven-and-a-half hours of sleep a night is normal for most adults and time lying awake on bed doesn't count, Poe says. While children need more sleep, babies need much more, roughly twice as much as adults. The large percentage of REM sleep in babies is in contrast to the amount of REM sleep observed in adult mammals across an enormous range of brain sizes and body sizes. Adult humans have five REM cycles during a full night of sleep and can have a few dreams in each cycle.

A good night's sleep is excellent medicine, Poe says. And it's free!

So make sure you take care of yourself and keep a window period of 8 hours for stress-free peaceful sleep.

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