How ’sleeping on it’ can help the prefrontal cortex regulate emotional responses, making us feel better in the morning

Instead of lying awake wor­ry­ing, we’re often told to “sleep on it” when mak­ing deci­sions both big and small. And there’s actu­al­ly a sci­en­tif­ic basis for this advice. Sleep can influ­ence our response to emo­tion­al sit­u­a­tions, and helps us to man­age our men­tal health.

To under­stand why sleep and emo­tions are so con­nect­ed, it’s impor­tant to first under­stand what hap­pens in the brain when we encounter some­thing emotive.

Two main brain regions inter­act to cre­ate emo­tion­al respons­es. The first is the lim­bic sys­tem, which is locat­ed deep in our brain. This acts as our emo­tion cen­tre, quick­ly eval­u­at­ing a sit­u­a­tion and help­ing us to decide how to react. His­tor­i­cal­ly, this region may have been impor­tant for humanity’s sur­vival, as it helps us react quick­ly in cer­tain sit­u­a­tions – if we encounter a dan­ger­ous preda­tor, for example.

But most of the time we need to adjust our ini­tial emo­tion­al response. This is where the sec­ond region – the pre­frontal cor­tex – comes in. Locat­ed just behind our fore­head, the pre­frontal cor­tex helps us to increase or decrease our emo­tion­al respons­es as nec­es­sary. So if we see a preda­tor (such as a bear) in the zoo, the pre­frontal cor­tex tells us we don’t need to pan­ic because it’s in an enclosure.

These regions need to be well-con­nect­ed in order to effec­tive­ly gen­er­ate and adjust our emo­tion­al respons­es. This is where sleep comes in. When we’re sleep deprived, the con­nec­tions between these areas weak­en, mak­ing the reac­tion in the lim­bic sys­tem stronger. Sleep loss not only increas­es our reac­tion to stress­ful events dur­ing the day, it also makes these reac­tions hard­er to change. This may be par­tic­u­lar­ly pro­nounced if you lose REM (rapid eye move­ment) sleep.

Stud­ies show that get­ting poor sleep makes us more like­ly to choose less effec­tive ways of man­ag­ing our emo­tions which could have a knock-on effect for our men­tal health. Imag­ine you’re expe­ri­enc­ing a dif­fi­cult work prob­lem. If you’re well rest­ed, you are more like­ly to be able to effec­tive­ly prob­lem solve, fix­ing the issue. But if you’re sleep deprived, you might avoid deal­ing with the prob­lem. Over time, this could have a neg­a­tive effect on wellbeing.

Sleep is also cru­cial for pro­cess­ing and con­sol­i­dat­ing mem­o­ries from our day. When we have emo­tion­al expe­ri­ences, sleep both helps us remem­ber these events and remove the asso­ci­at­ed feel­ings. This hap­pens in REM sleep, when activ­i­ty in most brain regions is sim­i­lar to when we’re awake. By reac­ti­vat­ing mem­o­ries dur­ing REM sleep, the asso­ci­at­ed feel­ings can be removed from the con­tent of the mem­o­ry. This is why “sleep­ing on it” real­ly can help you feel bet­ter in the morn­ing. Indeed, stud­ies have shown that, over time, improv­ing sleep can lead to less anx­i­ety, depres­sion, and stress, and increased life satisfaction.

– Joanne Bow­er is a Lec­tur­er in Psy­chol­o­gy at the Uni­ver­si­ty of East Anglia. This arti­cle was orig­i­nal­ly pub­lished on The Con­ver­sa­tion.

To Learn More:

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• NICE in the UK issues rec­om­men­da­tion for Sleepio app, the dig­i­tal cog­ni­tive behav­iour­al ther­a­py for insom­nia by Big Health