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(Lise Gagne/iStockphoto/Lise Gagne.iStockphoto)
(Lise Gagne/iStockphoto/Lise Gagne.iStockphoto)

An extra hour of sleep isn't all good news for your body clock Add to ...

It's almost here: the annual falling back of clocks and adjusted bedtimes as most of North America returns to standard time. As much as we may love an extra hour of daylight in the warmer months, the required schedule change is a controversial affair.

Aside from debates about how the time change affects energy costs for keeping lights on, or the economic impact of having more or less time to shop, one thing is clear: The quality and duration of sleep is affected with every arbitrary move of the clock.

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All the major functions in the body, from the regulation of temperature to hunger and tiredness, are synchronized by a master clock in the brain - a group of cells in the hypothalamus a few inches behind the eyes. The body's cycle, its circadian rhythm, repeats every 24 hours or so, and includes regular fluctuations in sleepiness and wakefulness.

Pushing a few buttons may quickly change the clock on your microwave, but it takes much longer to adjust the clock in your brain and its nightly progress through several distinct stages of sleep.

A good night's sleep involves several alternating cycles of these sleep stages. Acting as if it's only 10 p.m. when your body is at 11 p.m. disrupts this progression.

Moving the clocks forward in the spring can be even worse, because most of us begin the time change by skipping an hour of sleep altogether. The resulting sleep disruption takes a toll on mental processes that otherwise benefit from a regular sequence of sleep stages. Corresponding lapses in memory and concentration may help explain the increase in workplace injuries following switches to daylight-saving time.

It is tempting to think of the brain in terms of a battery that gets drained throughout an active day's use and needssix to eight hours of downtime to recharge. But the brain is not a slacker.

Instead of sitting idle while you snooze, this amazing organ is busily engaged in neuroplastic change.

Two sleep stages - slow-wave and rapid-eye-movement - are particularly important. The oscillating patterns of neural activity that accompany these stages are thought to influence how neurons connect and work together. The result, among other things, is enhanced learning and memory from the previous day's events. Indeed, getting a good night's sleep after learning something new can lead to better performance even without additional study.

Such benefits can be traced to memory-related activity in the hippocampus, a long curved structure within the medial temporal lobe on each side of the brain. While critical for initial memory formation, the hippocampus is not where the memories are ultimately stored. Instead, the bits of information that together comprise an event are represented and stored in neural traces distributed throughout regions of the brain's outer cortex.

Undisturbed sleep allows these evolving memories to be replayed in the brain by repeating specific patterns of activation in the hippocampus and cortical regions associated with a recent event. Subsequent performance is enhanced because the brain is rehearsing while you sleep, making the memory traces more durable.

So, how can we minimize the upcoming time shift's impact on our brain?

Research suggests our circadian rhythms adjust best bit by bit, over a number of days. Taking a nap also helps -even five to 10 minutes of shut-eye can aid learning and memory.

The best-functioning brains in the country may be in Saskatchewan next week: The folks there are smart enough to avoid the time-change silliness altogether.

Mark Fenske, co-author of The Winner's Brain: 8 Strategies Great Minds Use to Achieve Success, is an associate professor at the University of Guelph.

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