Not getting enough sleep? Here's why it could be affecting your memory
Researchers are discovering fascinating things about the links between sleep, how we remember things
It's time for bed, and in addition to my cosy red pyjamas decorated with hockey sticks, I'm wearing electrodes all over my body.
With wires sprouting from my scalp, chest and legs, I feel more like Frankenstein than Sleeping Beauty.
"Have a good night," sings out Stuart Fogel, as he shuts off the light in my austere bedroom at the Royal Ottawa Institute for Mental Health Research.
Then he's off to the laboratory — where my brain waves will be documented for the next eight hours — to search for clues about how memory works.
"It's hard to communicate the benefit that you can get from sleep, and the importance of sleep, when so many other things seem to be of greater importance in our daily lives," Fogel says.
Researchers have known for a while that sleep is essential to how we form memories. But Fogel, a professor at the University of Ottawa's Sleep Research Laboratory, is keen to uncover exactly how our brains process and synthesize those memories.
His research comes at a time when about a third of Canadian adults get less than seven hours of sleep a night on average, according to Statistics Canada.
And the consequences of sleep deprivation are far more serious than feeling dozy and worn out.
"What's intriguing is that sleep loss will have an impact on your ability to retain anything that you learn that's new," Fogel says.
The research also aims to shed light on how sleep deprivation may contribute to a condition that's on the rise in Western societies: dementia.
Sleep spindles
Generally, adults spend one-third of their lives sleeping. It's only in the past few decades that scientists have begun to understand some of the reasons why.
"The more we study this, the more we find how there's just so many aspects of sleep that are involved in memory processing," Fogel says.
Fogel has spent several years examining the relationship between memory and "sleep spindles," the brief bursts of brain activity which occur during deep sleep. These one- to two-second electrical pulses happen up to 1,000 times a night, and can be measured on an electroencephalogram (EEG).
Researchers believe these spindles show our brain taking what we learn each day and shifting it from the hippocampus, a limited space where we store recent memories, to the prefrontal cortex. That's the brain's "hard drive," where we store important memories for future reference — whether that's tomorrow, next week, or next year.
Sleep effectively cleans up the hippocampus, leaving us ready to take in fresh data.
"Memory centres that are recruited during learning are reactivated during sleep ... that's actually enhancing that memory trace and strengthening it, so that the next day we're better at the task," Fogel says.
What does that mean for a teenager who's up all night texting, or an adult working into the wee hours?
You may not learn as much.
More specifically, if you sleep six hours or less you'll have fewer spindles — and that means you may not permanently retain as much of what what you experienced that day.
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Early warning signs
Fogel's current research focuses on how sleep affects newly formed motor skills, such as learning to play a musical instrument or taking a slapshot.
Which explains why I'm lying in a massive MRI scanner before bedtime, madly tapping my fingers on buttons that move brightly-coloured blocks from one side of a screen to another.
To demonstrate his current research, Fogel has invited me to sleep overnight at the Royal Ottawa, along with two other test subjects — Nick Vanderberg, 23, and Tom Patterson, 60.
Patterson is what Fogel describes as an "optimum aging adult," a person with a good diet and no major health issues. During his working years, though, Patterson says he didn't sleep so well.
Since retiring, he's rediscovered the gym, which has improved his rest. But he also finds himself forgetting stuff.
"I talk about it a lot [with people my age]. Going into a room and saying, 'Hey, why did I come into this room again? What am I looking for?' That happens. It really does happen," Patterson says.
Fogel is studying healthy adults for insights into how sleep affects their motor memory skills. He hopes to determine if sleep therapy could help slow the onset of dementia.
"What we're hoping is that's going to give us a good sense of some important bio-markers for the early warning signs … that could be possible ways of staving off dementia, or mitigating the consequences, or perhaps finding novel treatments," Fogel says.
He enlisted Vanderberg, a doctoral student, to show how differently a young brain deals with memory and sleep.
In addition to the MRI scan, which allows his team to take pictures of brain activity, Fogel explains that the three of us will take a motor-skills test that involves repeatedly finger-tapping a specific sequence of numbers into a small keypad.
He asks us to enter the numbers – 4 1 3 2 4 – over and over, as quickly as we can. The computer measures our speed and accuracy as we tap furiously for 10 minutes.
"When you really accelerate your performance is when you actually start to chunk the numbers to make the execution of the sequence more efficient," Fogel tells us.
I feel as if I'm getting faster until, by the end, my fingers are numb.
Once all three of us brush our teeth and head to separate bedrooms, research assistants glue electrodes to specific spots on our bodies.
The novel part of Fogel's research is the combined use of the Royal's state-of-the-art MRI and the EEG. The electrodes, along with other equipment, measure our brain traces, eye movements, muscle activity, heart rate, leg movements and breathing.
After making sure the electrodes are on tight, it's time for us to nod off – and for Fogel to discover whether his lab rats learned anything.
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The sleep boost
Fogel bursts into my room at 6:30 a.m.
"Good morning! Ready for your test?"
I rub my eyes. I slept about eight hours, waking once to use the washroom. I recall it took a while to doze off again.
I groggily sit down at the computer. I hear Patterson and Vanderberg do the same in their bedrooms.
I clutch the keypad, tapping the sequence from the night before – 4 1 3 2 4. I feel faster, but I'm relieved when the student assistant tells me to stop so she can calculate our results.
As we wait, Fogel shows me what the EEG measured during my sleep.
"Your brain was probably pretty tired, I would say," he laughs.
He traces his finger along the squiggly lines that represent my brain waves. Within minutes of hitting the pillow, I was in Stage Two, a light sleep where spindles start to occur.
"You've got really nice, big spindles here ... these big bursts of activity," Fogel says, which sounds encouraging.
"That indicates you're probably reprocessing that information, reactivating those memory traces, integrating them into long-term memory stores."
We convene in the lab to hear the results. Patterson, the senior of the group, had a "broken and interrupted sleep." Vanderberg, the youngster, slept like a rock.
The graph shows all three of us improved our finger speed when our brains began to first process the new task, but our sleep gains were a different story.
The 23-year-old's fingers were even faster in the morning. Mine, too. But, as expected, the 60-year-old was tapping at the same rate as the night before.
As we age, Fogel explains, we don't get the same brain boost from sleep as when we were younger. That's because sleep spindles decrease in both magnitude and frequency.
"That's what we think is the important ingredient … the age-related changes in sleep are actually not allowing that reactivation and strengthening of the memory traces to take place in the same way as when you're younger," Fogel says.
While much remains to be learned about how sleep could be related to Alzheimer's and other forms of dementia, Fogel says it's important to emphasize what scientists do know: sleep is critical for everyone to improve their intellectual and physical performance.
Right now, that's a problem – Canadian adults are getting about an hour less sleep on average than in 2005, according to Statistics Canada.
"Our lives are being filled with more and more information, more and more activities," Fogel says.
"We really need less and less of that, in order to not compete with our time to get the sleep that we need."
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