How to Fix Your In­ter­nal Clock

Al­most ev­ery sys­tem in our body works on a 24-hour cy­cle. Here are the se­crets of cir­ca­dian rhythm—and how to get in sync.

Men's Journal - - FITNESS - By JOSEPH HOOPER

WE’VE LONG KNOWN that cir­ca­dian rhythm—the way our body func­tions line up with day and night—dic­tates our ideal sleep-wake sched­ule. Now, sci­en­tists are find­ing that al­most ev­ery sys­tem runs on a 24-hour clock. That makes it pos­si­ble to dial in on the ideal sched­ule for things like eat­ing, ex­er­cise, and even tak­ing med­i­ca­tion. Time it right and it could mean the dif­fer­ence be­tween skat­ing by and work­ing at max­i­mum ef­fi­ciency.

“Think of the mas­ter clock in your brain as an orches­tra con­duc­tor and the clocks in the rest of your body as the dif­fer­ent sec­tions of that orches­tra,” says Court­ney Peter­son,

a re­searcher at the Univer­sity of Alabama at Birm­ing­ham.

Ex­perts have long sus­pected that hu­mans are bound to an in­ter­nal clock. It is some­thing that they dis­cov­ered, in part, by look­ing at the plethora of health is­sues that be­fall shift work­ers, long-haul truck­ers, and oth­ers who work through the night and sleep dur­ing the day. For in­stance, those work­ers have an in­creased risk of cer­tain types of can­cer, car­dio­vas­cu­lar dis­ease, obe­sity, and de­pres­sion.

Here’s what hap­pens: When morn­ing light hits our eyes, it ac­ti­vates a cer­tain pro­tein, which, in turn, sends a sig­nal to the brain’s

hy­po­thal­a­mus that it’s time to get go­ing. The brain re­leases hor­mones through­out the body that wake up all the sys­tems. Body tem­per­a­ture rises, blood pres­sure goes up, and by mid­morn­ing you’re on high alert. The re­verse hap­pens when the sun goes down. For most, seven to nine hours of con­tin­u­ous sleep (go­ing to bed be­tween 10 p.m. and mid­night and wak­ing in the 6 a.m. to 8 a.m. range) is op­ti­mal.

So, now you’re awake, and it’s time to get go­ing. It’s been a while since your last meal, and your body wants to get fu­eled up first thing in the morn­ing, so if you’re a break­fast­skip­per, you may want to re­think. It ap­pears that our meta­bolic cir­ca­dian rhythm is set up so that mus­cle cells are most sen­si­tive to in­sulin—the hor­mone reg­u­lat­ing blood sugar—ear­lier in the day. Break­fast will prob­a­bly burn as en­ergy, while a late din­ner will store as fat.

In a small pilot study of pre­di­a­betic men, those who fol­lowed in­ter­mit­tent fast­ing—eat­ing all three meals in a six-hour pe­riod (mean­ing din­ner ended by 3 p.m.)—af­ter five weeks had re­duced their blood pres­sure by 11 points, on av­er­age, and in­creased their in­sulin sen­si­tiv­ity, which could help with weight loss.

It comes down to re­source dis­tri­bu­tion. Your body de­votes a lot of en­ergy and at­ten­tion to di­ges­tion, which is why you’d never go for a run right af­ter eat­ing a big meal. Putting more time be­tween din­ner and bed­time means your body can fo­cus on restora­tive sleep and re­pair­ing tis­sue, says Satchin Panda, a bi­ol­o­gist at the Salk In­sti­tute and au­thor of The Cir­ca­dian Code. Since eat­ing din­ner mid­day is im­prac­ti­cal, Panda sug­gests keep­ing meals in a 12-hour win­dow or less, if you can: break­fast at 7 a.m. and din­ner by 7 p.m.

Get on the right sched­ule and your body puts those calo­ries to good use. Peter­son’s study in the jour­nal Cell Me­tab­o­lism sug­gests that eat­ing per your cir­ca­dian clock re­duces the amount of meta­bolic “garbage” that builds up in cells, what bi­ol­o­gists call ox­ida­tive stress. Too much ox­ida­tive stress can cause inf lam­ma­tion, which is a driver of dis­ease.

As for ex­er­cise, late af­ter­noon is ideal for cir­ca­dian syn­chronic­ity. A re­view of re­search from the Univer­sity of Ber­gen in Nor­way finds that per­for­mance usu­ally peaks mid­day and later. For in­stance, swim­mers are faster in the evening even if they’re used to hit­ting the pool first thing in the morn­ing. And if you’re look­ing to PR a strength and power move, like a back squat or broad jump, you get bet­ter at those as the day goes on (though ex­er­cis­ing at night can pre­vent some peo­ple from fall­ing asleep eas­ily, mak­ing this bit of in­tel a catch-22).

And sci­en­tists are only scratch­ing the sur­face. For in­stance, an­i­mal and hu­man stud­ies re­veal that even the im­mune sys­tem has a clock. It may help ex­plain why peo­ple have more heart at­tacks in the morn­ing, or why the ach­i­ness from arthri­tis de­creases as the day goes on. And it might be why shift work­ers, whose sleep-wake sched­ules are con­stantly chang­ing, have a greater risk of cer­tain au­toim­mune dis­eases than the rest of the pop­u­la­tion.

Un­cov­er­ing the im­mune sys­tem’s clock has ex­cit­ing ap­pli­ca­tions. It could mean that vac­cines like the flu shot could be more ef­fec­tive by tim­ing them. “The im­pact is un­der­ap­pre­ci­ated,” says Paul Frenette, M.D., a medicine and stem-cell re­searcher at the Al­bert Ein­stein Col­lege of Medicine in New York. “There could be sig­nif­i­cant ben­e­fits to chronother­apy— ad­min­is­ter­ing cer­tain drugs and ther­a­pies, such as chemo­ther­apy, at the right time of day.”

So go with the cir­ca­dian f low. Get up with the sun or not too long af­ter. And throw open the shades or go out for a run. Ex­po­sure to out­door light boosts your mood, pro­tects against de­pres­sion, and sets you up for the early meal plan.

Ob­vi­ously, a late din­ner or tick­ets to a bas­ket­ball game can get in the way of stick­ing to your op­ti­mal cir­ca­dian sched­ule. To get a solid night’s sleep, be­low are a few sci­en­tif­i­cally backed meth­ods for max­i­miz­ing shut­eye—with­out a pre­scrip­tion.

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