Scientists Pinpoint Why Some of Us Are Light Sleepers


My husband seems to be able to sleep through any noise in the middle of the night (especially, it seems, if it’s coming from my son’s room).  Meanwhile, I leap into an action stance at the slightest peep.  I’ve always wondered if I created this by being the alert one at night—his mind is free to screen out noises. Or were we wired that way?

A study highlighted in the New York Times Well blog has found evidence for the second conclusion–an underlying brain difference between deep and light sleepers. The researchers from Massachusetts General Hospital monitored the brain activity of sound sleepers and found that the thalamus regions of these subjects created especially big “sleep spindles”—high-frequency spikes in activity, deep in the brain.  The bigger the spike, the better the sleeper. Scientists think the spindle activity might keep sensory information from passing through the thalamus (this region is kind of like the brain’s filter or communication hub), so the person isn’t woken up.

The new data helps doctors and researchers pinpoint where certain people’s sleep problems might come from.  Insomnia is varied—some people have trouble falling asleep, some staying asleep, and some waking at the earliest light. Small sleep spindles could be the problem with the staying asleep crowd.

A note that might peak the interest of anyone who takes sleeping pills: one of the scientists’ conclusions is that we could be going about sleep medications all wrong.

Sleeping meds work by sedating the whole brain, but what the researchers have found is that an active thalamus (not a dulled one) might be the key to keeping some patients in a deep sleep.  The conclusion being that an eventual drug to target the thalamus and encourage spindles might be a more effective route for some.

Still, I wonder, does my husband have unusually robust activity in his thalamus at night? And even so, did we create this pattern together?  I don’t think I was always so alert in the wee hours–I think motherhood may have trained my brain to be ready for action.

Image: Wikimedia/ljustam

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