Scientists in the US claim to have a new explanation for why we sleep: in the hours spent slumbering, a rubbish disposal service swings into action that cleans up waste in the brain.

Through a series of experiments on mice, the researchers showed that during sleep, cerebral spinal fluid is pumped around the brain, and flushes out waste products like a biological dishwasher.

The process helps to remove the molecular detritus that brain cells churn out as part of their natural activity, along with toxic proteins that can lead to dementia when they build up in the brain, the researchers say.

Maiken Nedergaard, who led the study at the University of Rochester, said the discovery might explain why sleep is crucial for all living organisms. "I think we have discovered why we sleep," Nedergaard said. "We sleep to clean our brains."

Writing in the journal Science, Nedergaard describes how brain cells in mice shrank when they slept, making the space between them on average 60% greater. This made the cerebral spinal fluid in the animals' brains flow ten times faster than when the mice were awake.

The scientists then checked how well mice cleared toxins from their brains by injecting traces of proteins that are implicated in Alzheimer's disease. These amyloid beta proteins were removed faster from the brains of sleeping mice, they found.

Nedergaard believes the clean-up process is more active during sleep because it takes too much energy to pump fluid around the brain when awake. "You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can't really do both at the same time," she said in a statement.

According to the scientist, the cerebral spinal fluid flushes the brain's waste products into what she calls the "glymphatic system" which carries it down through the body and ultimately to the liver where it is broken down.

Other researchers were sceptical of the study, and said it was too early to know if the process goes to work in humans, and how to gauge the importance of the mechanism. "It's very attractive, but I don't think it's the main function of sleep," said Raphaelle Winsky-Sommerer, a specialist on sleep and circadian rhythms at Surrey University. "Sleep is related to everything: your metabolism, your physiology, your digestion, everything." She said she would like to see other experiments that show a build up of waste in the brains of sleep-deprived people, and a reduction of that waste when they catch up on sleep.

Vladyslav Vyazovskiy, another sleep expert at Surrey University, was also sceptical. "I'm not fully convinced. Some of the effects are so striking they are hard to believe. I would like to see this work replicated independently before it can be taken seriously," he said.

Jim Horne, professor emeritus and director of the sleep research centre at Loughborough University, cautioned that what happened in the fairly simple mouse brain might be very different to what happened in the more complex human brain. "Sleep in humans has evolved far more sophisticated functions for our cortex than that for the mouse, even though the present findings may well be true for us," he said.

But Nedergaard believes she will find the same waste disposal system at work in humans. The work, she claims, could pave the way for medicines that slow the onset of dementias caused by the build-up of waste in the brain, and even help those who go without enough sleep. "It may be that we can reduce the need at least, because it's so annoying to waste so much time sleeping," she said.

A poem written by a teenager diagnosed with cancer.

Have you ever watched kids on a merry-go-round? Or listened to the rain slapping on the ground?
Ever followed a butterfly's erratic flight? Or gazed at the sun into the fading night?
You better slow down don't dance so fast, time is short the music won't last.

Do you run through each day on the fly? When you ask, "How are you?" Do you hear the reply?
When the day is done, do you lie in your bed, with the next hundred chores running through your head?
You'd better slow down don't dance so fast, time is short the music won't last.

Ever told your child, We'll do it tomorrow? And in your haste, not see his sorrow?
Ever lost touch, let a good friendship die, 'cause you never had time to call and say, 'Hi'
You'd better slow down don't dance so fast, time is short the music won't last.

When you run so fast to get somewhere, you miss half the fun of getting there.
When you worry and hurry through your day, it is like an unopened gift, thrown away.
Life is not a race do take it slower, hear the music before the song is over.

Airline Tickets

You'll get the lowest price for a domestic flight approximately 47 days in advance. The prime booking window is from 114-27 days before departure. Fares are highest within 14 days of departure.

Appliances

New models hit stores in September and October, so older models are cleared out at big discounts. Presidents' Day, Memorial Day, Labor Day, and Black Friday also have good sales.

Cars and Trucks

You'll get the best price on a new vehicle early in the fall, when new models arrive and dealers offer discounts, cash rebates, and low- or no-interest financing on prior models. Also, negotiate your deal at the end of the month, when dealers need to make sales quotas.

Bicycles

You'll get the best deals in January and February and good markdowns in September.

Big Screen TVs

Thanksgiving week has great prices on high-definition TVs, plus door-busters at up to 50% off. Name brands run deals around the Super Bowl to make room for new models.

Computers

Laptops are discounted in late March and early April, as the Asian manufacturing cycle ends; August and September, for back-to-school; and Thanksgiving (Black Friday and Cyber Monday). Get deals on Apple gear when new models come out, or save on a refurbished model no more than a year old.

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Booking nine months to a year ahead will get you the best price on a good cabin, especially if you use an agent with cruise experience.

Furniture

Best prices are in January, July, and Presidents' Day.

Grills

Prices drop after Labor Day, with the best deals in October, although there's less selection.

Jewelry

Forget Valentine's Day, the best sales are in May (after Mother's Day), as well as July and August.

Lawnmowers

Retailers cut prices in early spring, with deals peaking in April. There are good discounts for Father's Day, then clearance prices after Labor Day.

Mattresses

Shop Presidents' Day and Labor Day, with Memorial Day offering the best selection and biggest discounts.

Outdoor Furniture

Prices are rock-bottom in October and November, but if you want selection, pay a little more at late summer sales.

Refrigerators

May is the best month, especially Mother's Day and Memorial Day.

Wedding Dresses

Bridal shops cut prices in early December to make room for new inventory, so proposals should be made before the holidays!

Now may be the best time to buy a new home or to refinance your current one at a lower rate, or to fund improvements while rates are still low. There are a wide range of financing options—feel free to contact us any time.... Have a great day!