Land of nod

Weekend Herald - - Bring On The Weekend - Michelle Dick­in­son Dr Michelle Dick­in­son, also known as Nanogirl, is an Auck­land Uni­ver­sity nan­otech­nol­o­gist who is pas­sion­ate about get­ting Ki­wis hooked on science. Tweet her your science ques­tions @medick­in­son

The health ben­e­fits of a de­cent night’s sleep have been well sig­nalled — now, there’s new re­search to show just how dan­ger­ous a lack of sleep might prove. Michelle Dick­in­son re­veals all in her Science col­umn to­day.

Are you feel­ing tired? You are not alone; more than a third of New Zealan­ders re­port ei­ther not get­ting enough sleep, or that the qual­ity of their sleep is com­pro­mised.

It’s well known that sleep de­pri­va­tion has neg­a­tive ef­fects on at­ten­tion, mood, mem­ory, re­ac­tion time and de­ci­sion-mak­ing, but just how dan­ger­ous could be­ing over­tired be?

New re­search out this week in the jour­nal Na­ture Com­mu­ni­ca­tions tried to put some measurements on tired brains, and the re­sults show tired­ness could have some se­ri­ous con­se­quences.

The study in­volved 12 pa­tients, who were sched­uled to have surgery to help with their epilepsy. The pa­tients had elec­trodes im­planted in their brains and were kept awake overnight.

Dur­ing the night, they were asked to carry out a sim­ple cog­ni­tive ex­er­cise which in­volved look­ing at pic­tures and then quickly press­ing one of two but­tons to iden­tify if the pic­ture was of a hu­man face or not.

As the pa­tients be­came sleepier, they were less ac­cu­rate at cor­rectly iden­ti­fy­ing the pic­tures and their re­sponse times were slower.

To try to work out why the sleepy pa­tients were per­form­ing poorly, the re­searchers used im­planted elec­trons to mea­sure sig­nals from in­di­vid­ual neu­rons in their brains dur­ing the test.

They found that in the tired pa­tients, their neu­rons re­sponded more slowly, fired sig­nals more weakly and trans­mit­ted for longer com­pared with the brain cells from well-rested brains.

They also found ev­i­dence that sug­gested parts of the tired brain were try­ing to take lo­calised naps, with ar­eas fir­ing more slowly and show­ing sleep-like slow brain­waves.

This re­gional brain nap­ping has been seen be­fore in sleep-de­prived rats whose brains also seemed to show lo­calised slow brain cell fir­ing and a re­duced abil­ity to per­form cog­ni­tive tasks.

Know­ing that tired brains re­duce our re­ac­tion time and dan­ger iden­ti­fi­ca­tion ac­cu­racy, as well as make us per­ceive and re­act to the world more slowly, opens up ques­tions around the po­ten­tial dan­gers of driv­ing or us­ing ma­chin­ery while tired.

We al­ready know that the

per­for­mance of the brain de­clines with al­co­hol con­sump­tion, and these new re­sults show that tired­ness while driv­ing could be just as deadly.

If it takes your tired neu­rons more time to re­spond to a sim­ple photo iden­ti­fi­ca­tion game, imag­ine the con­se­quences of a slower re­ac­tion re­sponse if a pedes­trian walked out in front of your car.

Sadly, un­like a breath-al­co­hol test, there is no easy test to ex­ter­nally mea­sure how tired a per­son’s brain is, so the re­spon­si­bil­ity lies with the in­di­vid­ual to make good de­ci­sions about their men­tal clar­ity be­fore driv­ing.

There is no set num­ber for the amount of qual­ity sleep we need to func­tion prop­erly.

Stud­ies sug­gest it hov­ers around eight hours for most of us, with some need­ing more and some need­ing less. The gen­eral rule is that if you wake up tired and spend the day long­ing for a nap then you are prob­a­bly not get­ting enough sleep.

Wear­able tech­nolo­gies such as smart watches can help us to mon­i­tor our sleep cy­cles and track them against our mood to de­ter­mine in­di­vid­ual pref­er­ences.

Un­like eat­ing and breath­ing, we still don’t fully un­der­stand why peo­ple need to sleep, but we do know that sleep is es­sen­tial and get­ting enough sleep is im­por­tant for your health.

Some the­o­ries link sleep to the time our brain needs to store its mem­o­ries from the day, oth­ers link sleep to hor­mone reg­u­la­tion. What­ever it is, sleep de­pri­va­tion has been linked to weight gain, in­flam­ma­tion, di­a­betes and heart dis­ease.

Life is busy, and get­ting enough sleep is tough, but pri­ori­tis­ing sleep could ac­tu­ally help you to live longer, health­ier and less grumpy lives.

Pic­ture / 123RF

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