Your brain is a washing machine.
Granted, it's an incredibly complex, highly developed washing machine. But the cleaning aspect is roughly the same.
There are still many mysteries of the brain... a lot we don't understand. But we now know not only how the brain's self-cleaning feature works, but what it means for preventing Alzheimer's disease.
A study published last week in Science shines light on just how this works. It focused on measuring fluid in your brain called cerebrospinal fluid (CSF). This is a clear liquid that your brain makes out of your blood. It washes over and through your brain and spinal cord.
We know that CSF cushions these areas and carries nutrients around. But that's all we really thought it did.
This study from Boston University figured out CSF also clears toxins and waste out of our brains while we sleep.
The researchers used MRI tests to watch participants as they slept. What they found was that the CSF came in waves washing over the brain on a repeated cycle – almost like a slow washing machine rotating.
More interesting, the brain sent an electrical signal just before the wave started. This signal pattern matches something we've already seen – the slow brain waves we produce during deep sleep.
My friend Param Dedhia wrote about this last month:
There are two types of sleep – non-REM "deep sleep" and REM "dream sleep." (REM stands for "rapid eye movement.")
Deep sleep happens during the first half of your sleep. And it's during this time of rest when your body repairs itself. Your body releases growth hormones and repair proteins – this is why your workout continues after you sleep. Your body repairs and regenerates your muscles as you sleep. Sleep is just as important for building muscle as weight-bearing exercise.
Deep sleep is also when we start to build memory. This type of sleep helps your brain transfer memories from the short-term storage area in your hippocampus to the long-term storage area of your cortex. You need sleep to form these memories.
We already know deep sleep is the restorative sleep for our bodies. But it's also the restorative cleaning cycle for our brains.
Here's the kicker... Folks with Alzheimer's have reduced deep sleep brain waves. The Boston University team believes that this is the connection – if you don't get enough deep sleep, you lose the ability to turn on this wash cycle with CSF. Then waste builds up and leads to the hallmarks of Alzheimer's – "tangles" and plaques.
An Alzheimer's diagnosis has three defining characteristics...
1. Memory impairment
2. Plaque buildup in the brain tissue
3. "Tangles" of phosphorylated tau proteins
Both the amyloid plaques and the tau tangles can be seen on medical scans. These are the defining traits that distinguish Alzheimer's from less severe cases of dementia.
If this sounds familiar, it's because we talked about a "trash disposal" in our brains that could slow Alzheimer's.
We've written before about something called the glymphatic system. It didn't appear in medical journals until 2012, and it wasn't until just a year or two ago that it started to be more widely studied. This system is a network that runs through our brains and clears out trash and waste.
Guess what... the glymphatic system includes our CSF pathways.
We already knew that sleep turns on the glymphatic system... But we didn't understand how it worked. This new research finally answers that question.
That's why sleep – deep, quality sleep – is so crucial for our health. We now have a pile of evidence showing that good sleep prevents Alzheimer's.
And it's just in time – this past weekend, we set our clocks back. That meant an extra hour of sleep, but don't let this interfere with your usual schedule.
One of the best sleep tips is to stick to the same bedtime. Training your body and brain to rest at a certain time will lead to a better, easier time going to sleep. As we get into fewer hours of daylight and an increasing number of social obligations, stick to this schedule. Make sleep a priority this season... It's one of the best ways to take care of your brain.
What We're Reading...
- Did you miss it? Sleep guru Param Dedhia on the types of sleep.
- More on that Boston University study.
- Something different: Turns out our guts are password-protected.
Here's to our health, wealth, and a great retirement,
Dr. David Eifrig and the Health & Wealth Bulletin Research Team
November 5, 2019