Tag Archives: sleep

Together, Unconscious: We All Sleep

One con­stant that con­nects us all in some way is that–at the end of our day–we lie down and slowly slip into a state of reduced or absent con­scious­ness and become at the mercy of our fel­low man. Every day we fall asleep: we have done so for mil­lions of years and will con­tin­ue to do so.

This hum­bling thought was inspired by Dav­id Cain’s short dis­quis­i­tion on how the act of sleep­ing is some­thing that unites us togeth­er, all around the world. David’s post didn’t quite take the route I was expect­ing after read­ing the (won­der­ful) excerpt below1, but is still def­in­itely worth a read.

It’s an inter­est­ing quirk of Moth­er Nature — that she insists on tak­ing us down to the ground like that, every day, no mat­ter who we are. For all of us, the act of leav­ing con­scious­ness is the same, it’s just our set­tings and situ­ations — which bookend that uncon­scious­ness — where we dif­fer.

via Link Banana

1 I was expect­ing the post to con­cen­trate on the first sen­tence (leav­ing con­scious­ness), rather than the second sen­tence (sleep as a con­nect­or).

Illness Susceptibility and Sleep Quality

I’ve been ill for a few weeks and I was fairly sure (in my ama­teur opin­ion) that it was related to a sig­ni­fic­ant lack of sleep over the last couple of months. Upon return­ing to full health I decided to do some quick research on my favour­ite top­ic: sleep.

In one recent study look­ing at sleep habits and res­ult­ing sus­cept­ib­il­ity to the com­mon cold it was found that both sleep length and sleep qual­ity were “import­ant pre­dict­ors of immunity and, in turn, sus­cept­ib­il­ity”.

Spe­cific­ally, “those who slept an aver­age of few­er than sev­en hours a night […] were three times as likely to get sick as those who aver­aged at least eight hours”. Fur­ther­more, people who had 92% sleep effi­ciency were five and a half times more sus­cept­ible com­pared to those with 98% sleep effi­ciency (defined as the per­cent­age of time in bed actu­ally asleep).

The New York Times art­icle that led me to this study con­tin­ues:

Sleep and immunity, it seems, are tightly linked. Stud­ies have found that mam­mals that require the most sleep also pro­duce great­er levels of dis­ease-fight­ing white blood cells — but not red blood cells, even though both are pro­duced in bone mar­row and stem from the same pre­curs­or. And research­ers at the Max Planck Insti­tute for Evol­u­tion­ary Anthro­po­logy have shown that spe­cies that sleep more have great­er res­ist­ance against patho­gens.

The more you know… (the more you sleep?)

Update: I’ve briefly men­tioned this study on Lone Gun­man before, but I think the cog­nit­ive impact was the most inter­est­ing tit­bit in that Jonah Lehr­er art­icle.

Gradual Sleep Deprivation, Obesity and Cognitive Impairment

By get­ting less than our required amount of sleep over an exten­ded peri­od of time (two weeks, for example) we are increas­ing our risk of obesity and impair­ing our cog­nit­ive abil­it­ies without even being aware of it.

That’s the con­clu­sion from a short art­icle sum­mar­ising the sur­pris­ing effects of gradu­al sleep depriva­tion:

Research­ers […] restric­ted volun­teers to less than six hours in bed per night for two weeks. The volun­teers per­ceived only a small increase in sleep­i­ness and thought they were func­tion­ing rel­at­ively nor­mally. How­ever, form­al test­ing showed that their cog­nit­ive abil­it­ies and reac­tion times pro­gress­ively declined [until] they were as impaired as sub­jects who had been awake con­tinu­ously for 48 hours.

Moreover, […] too little sleep changes the body’s secre­tion of some hor­mones. The changes pro­mote appet­ite, reduce the sen­sa­tion of feel­ing full after a meal, and alter the body’s response to sug­ar intake—changes that can pro­mote weight gain and increase the risk of devel­op­ing dia­betes. […]

A recent review […] of the large stud­ies that fol­lowed people over time agreed that short sleep dur­a­tion was asso­ci­ated with future weight gain. […] For example, [one study] showed an inverse cor­rel­a­tion between sleep dur­a­tion and obesity in high-school-age stu­dents. The short­er the sleep, the high­er the like­li­hood of being over­weight, with those get­ting six to sev­en hours of sleep more than two and a half times as likely to be over­weight as those get­ting more than eight hours. […]

The good news is that these effects can be reversed by get­ting an adequate amount of sleep. […] Allow­ing the study sub­jects to sleep 10 hours for two con­sec­ut­ive nights returned the hor­mones to nor­mal levels and lowered hun­ger and appet­ite rat­ings by almost 25 per­cent.

via @finiteattention

Routine, Sleep and Premature Death

Sleep­ing for less that six hours a night is cor­rel­ated strongly with an increased risk of pre­ma­ture death over a 25-year peri­od (a 12% increase in the like­li­hood of your pre­ma­ture death, to be exact).

That’s the con­clu­sion from an extens­ive report (study­ing 1.5 mil­lion people) con­vin­cingly show­ing the link between qual­ity sleep and one’s health/well-being.

The study looked at the rela­tion­ship between sleep and mor­tal­ity by review­ing earli­er stud­ies from the UK, US and European and East Asi­an coun­tries.

Pre­ma­ture death from all causes was linked to get­ting either too little or too much sleep out­side of the “ideal” six to eight hours per night.

But while a lack of sleep may be a dir­ect cause of ill health, ulti­mately lead­ing to an earli­er death, too much sleep may merely be a mark­er of ill health already.

That last bit’s import­ant (cor­rel­a­tion not caus­a­tion), with one research­er call­ing sleep the “lit­mus paper to phys­ic­al and men­tal health”.

Anoth­er report in the same journ­al (Sleep) demon­strated the import­ance of a stable daily routine in get­ting a good night’s sleep (although thus far it has only been shown in the eld­erly):

Increased sta­bil­ity in daily routine […] pre­dicted short­er sleep latency, high­er sleep effi­ciency and improved sleep qual­ity. […] Main­ten­ance of daily routines is asso­ci­ated with a reduced rate of insom­nia in the eld­erly.

So… stop your happy-go-lucky, spur-of-the-moment, dev­il-may-care life­style; live to a timetable; live longer?

Sleep for Creativity

Dreams are not “mean­ing­less nar­rat­ives” but are “layered with sig­ni­fic­ance and sub­stance”, laments insom­ni­ac Jonah Lehr­er as he con­siders the import­ance of dream­ing for cre­ativ­ity:

A group of stu­dents was giv­en a tedi­ous task that involved trans­form­ing a long list of num­ber strings into a new set of num­ber strings. This required the sub­jects to apply a painstak­ing set of algorithms. How­ever, […] there was an eleg­ant short­cut, which could only be uncovered if the sub­jects saw the subtle links between the dif­fer­ent num­ber sets. When left to their own devices, less than 25 per­cent of people found the short­cut, even when giv­en sev­er­al hours to mull over the task. How­ever, when [the research­er, Jan Born,] allowed people to sleep between exper­i­ment­al tri­als, they sud­denly became much more clev­er: 59 per­cent of all par­ti­cipants were able to find the short­cut. Born argues that deep sleep and dream­ing “set the stage for the emer­gence of insight” by allow­ing us to men­tally rep­res­ent old ideas in new ways.

So that’s anoth­er good reas­on to sleep well.

Before look­ing at how sleep is “an essen­tial com­pon­ent of cre­ativ­ity”, Lehr­er also describes this fas­cin­at­ing study: a selec­tion of rodents spent their day run­ning around a cir­cu­lar track, hav­ing their brain activ­ity mon­itored. Once the anim­als fell asleep, the research­ers noted that the brain activ­ity dis­played was identic­al to that dis­played while they were actu­ally run­ning around the track (i.e. they were dream­ing about run­ning). On fur­ther exam­in­a­tion, the research­ers then dis­covered that they could also pre­dict pre­cisely where on the track the rodents were at any giv­en point in their dream.