Dear Science

Dear Science,

When the weather is hot (like it is today), I feel stupid. It’s
like my brain just melts and I drop about 30 IQ points. Is this
actually possible, or is it all psychological? I spent about 15 minutes
buying a two-liter bottle of soda today, and it wasn’t because I had to
wait in line at the register—it was because I couldn’t operate
the self-checkout to save my life. Can I blame this on the heat, or is
it all on me?

Hot Head

Science is trying to write this column on a really scorching
day in Seattle. It’s taking forever. This paragraph has been
rewritten four times—eyes thick, fingers clumsy, and attention
wandering throughout the room, street, city. Hot Head, you aren’t
alone; heat makes us all stupid and slow.

Our brains have a pretty potent cooling system. All the blood
pulsing through your brain delivers oxygen first, and then whisks away
the heat generated when the oxygen is used with sugar to make energy.
The blood then runs up through the bridging veins right to the top of
the head—positioned like an internal Mohawk. The heat then
dumps out right there, causing sweat to run right down your face.
(Consider this yet another reason why bald men should be respected.) On
a normal day, this all works splendidly. On a hot day, where the top
of your head is probably being baked, your blood temperature creeps
upward, making the inside of your skull somewhat like a crappy car that
needs the heater to be on in order to run in the summer. Any brain
temperature above 40 degrees Celsius, easily reached if you’re doing
anything active on a hot day, starts wreaking havoc.

The monoamine neurotransmitters—serotonin, dopamine, and
norepinephrine—seem to have a hard go of things as the
temperature climbs. The neuroscientists cannot agree what exactly
goes on with serotonin (and mutter about not being able to slice
open the brains of overheated athletes to get at a definitive
answer). Taking the drug buspirone, which acts like serotonin in the
brain, makes athletes fatigue more quickly in the heat—so don’t
go grab your Prozac and hope to make it all better.

Dopamine is critical for controlling movement—and not
seeing and hearing things that aren’t actually there. Dopamine,
in the right amounts in the right places of the brain, is your friend.
Heat seems to do something with dopamine levels and distribution in the
brain. The closest we can really get to understanding all of this is in
the brains of overheated and tired rats; once rat brains hit that magic
40 degrees Celsius, they start to shut down. That’s all to say you
should ice-pack your neck if you want to think in the next heat
wave.

Swelteringly Yours,

Science

Send your science questions to
dearscience@thestranger.com.