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How to walk upright and stop living in a cave

Call me ar­ro­gant, but I’d rather op­ti­mize my in­door en­vi­ron­ment than try to spend more time in the capri­cious out­doors. I think it’s de­featism to give up on im­prov­ing our in­door spaces and re­sign our­selves to the fickle weather and sea­sons.

If I was go­ing to cre­ate an ideal en­vi­ron­ment for a hu­man, I think there are sev­eral things I would in­clude that we rou­tinely fail to in­clude in our homes and of­fices.


Our in­door light­ing sit­u­a­tion usu­ally sucks. The fact that “nat­ural light­ing” is a sell­ing point in real es­tate shows how ter­ri­ble a job we are do­ing in this de­part­ment. We rely on the sun nat­u­rally pro­vid­ing us with suf­fi­cient light, and if it’s an over­cast day or the days have grown shorter in the win­ter, then I guess we’re shit out of luck.

Usu­al­ly, in­door ar­eas are around 50-500 lux. This is hun­dreds of times dim­mer than the sun­light. Clear­ly, we weren’t de­signed to thrive in such dim en­vi­ron­ments, and sci­ence does ver­ify a con­nec­tion be­tween brighter light and alert­ness. If we don’t want to be sleepy like it’s night­time, we should­n’t light our rooms like it’s night­time. For some, the ef­fects of dim light­ing go be­yond sim­ple lethargy and, es­pe­cially in the win­ter, cause se­ri­ous mood prob­lems like sea­sonal af­fec­tive dis­or­der or the win­ter blues. This is com­mon, but it’s not nec­es­sary. Bright light, par­tic­u­larly blue light, can also gen­er­ally boost mood and may be a com­pa­ra­ble stim­u­lant to caf­feine. (Those who are prone to ma­nia should be care­ful, as in­tense light can trig­ger ma­nia or hy­po­ma­nia in those pre­dis­posed.) Brighter light­ing can also help cir­ca­dian rhythm is­sues (which I, for ex­am­ple, have strug­gled with for years), both by en­train­ing your cir­ca­dian rhythm so your body bet­ter knows when it’s day, and by short­en­ing it if it’s too long.

Light­ing is­n’t as ex­pen­sive as it used to be, so we can do bet­ter than we have in the past. The cost of elec­tric­ity for LED light­ing is now neg­li­gi­ble, and the only real fac­tor is the cost of the bulbs them­selves. Reach­ing for the full 100,000 lux of sun­light would still be pro­hib­i­tively ex­pen­sive, but go­ing for at least 10,000 lux is doable with only a few hun­dred dol­lars. I won’t go into specifics here, but you can get more in­for­ma­tion on spe­cific light­ing se­tups here or here. In par­tic­u­lar, get bulbs with a color tem­per­a­ture close to sun­light (5600k), but make sure the bulbs have a goodgood means 90+ Color Ren­der­ing In­dex (CRI), oth­er­wise the light will feel harsh.

I rec­om­mend putting any bright light­ing you buy for your home on elec­tri­cal timers so you don’t ac­ci­den­tally leave them on dur­ing the evening and screw up your sleep. You may also want to set your phone/­com­puter bright­ness on a timer, if you can. The goal is to mimic the nat­ural day/night cy­cle of our evo­lu­tion­ary en­vi­ron­ment, but with­out all the pesky volatil­ity of na­ture. You can get pro­grams like f.lux too, which re­duce the amount of blue light emit­ted by your de­vice in the evening, but in my ex­pe­ri­ence this is­n’t good enough and re­duc­ing the ac­tual bright­ness of the de­vice at night is also im­por­tant.

“But what about vi­t­a­min D? Just go out­side!” This is ter­ri­ble ad­vice, and I hear it too of­ten. Sun­light is a pow­er­ful car­cino­gen, and vi­t­a­min D sup­ple­ments are not, and they’re cheap.

Car­bon diox­ide

Car­bon MON-ox­ide is the deadly one you prob­a­bly al­ready have a mon­i­tor for in your house. Car­bon DI-ox­ide is the fee­ble cousin of car­bon monox­ide, but it still has a neg­a­tive ef­fect on hu­man health: high (but common)1,000 ppm or higher lev­els im­pairs our abil­ity to think. Just what you don’t want in an of­fice. High lev­els may also have a neg­a­tive long-term im­pact in other ar­eas of our health.

Hold your breath. When it sucks and you de­cide to start breath­ing again, it’s car­bon diox­ide buildup, not lack of oxy­gen, caus­ing you to feel panic and the need to breath. Car­bon diox­ide is a tox­in. And we breath it out into poorly ven­ti­lated rooms, where the lev­els can rise to dou­ble or triple what they are outdoorsaround 400 ppm.

Sev­eral stud­ies have shown sig­nif­i­cant (tem­po­rary) cog­ni­tive im­pair­ments due to car­bon diox­ide lev­els over 1,000 ppm, but such lev­els are commonI recently bought a carbon dioxide meter and found such levels in my home. in poorly ven­ti­lated shared spaces. For­tu­nate­ly, the so­lu­tion is sim­ple: open a win­dow. Un­for­tu­nate­ly, this does­n’t work when it’s rain­ing, or when it’s too hot out­side, or when it’s too cold out­side… In par­tic­u­lar, I have to con­tend with Cana­dian win­ters, which means open­ing the win­dow is a valid strat­egy for a mi­nor­ity of the year un­less I buy an ex­pen­sive heat re­cov­ery ven­ti­la­tor. I don’t have a good so­lu­tion for mit­i­gat­ing car­bon diox­ide buildup in the win­ter. Let me know if you do.

And, by the way, plants won’t work. They won’t suck up nearly enough car­bon diox­ide. You would need hun­dreds of plants per per­son, or roughly a dozen ful­l-­size trees per per­son, to off­set the car­bon diox­ide ex­haled by hu­mans in a room.

A fun fact: if we don’t stop pump­ing car­bon diox­ide into the at­mos­phere, then in about a cen­tu­ry, car­bon diox­ide out­doors may reach cog­ni­tively im­pair­ing lev­els. Then what do we do?

Tem­per­a­ture and Hu­mid­ity

High­/low hu­mid­ity and high­/low tem­per­a­ture both lead to dis­com­fort and lower scores on con­cen­tra­tion mea­sures. Peo­ple gen­er­ally have tem­per­a­ture un­der con­trol, or at least it’s some­thing they’re aware of. Hu­mid­ity is less com­mon to mea­sure, but a $10 hy­grom­e­ter should help you get your in­door space to the ideal 30-50% hu­mid­ity range if it is­n’t al­ready. Air con­di­tion­ers also tend to re­duce hu­mid­ity as well as tem­per­a­ture, so air-­con­di­tion in the sum­mer and use a hu­mid­i­fier in the win­ter.

At night, drop the tem­per­a­ture a few de­grees if you can; It’s eas­ier to sleep in a cool room. I won­der how many hours of sleep have been re­claimed al­ready due to the ad­vent of smart ther­mostats.

Back­ground Noise

I imag­ine this fac­tor is more sub­jec­tive than the oth­ers, but too loud is dis­tract­ing, even ag­gri­vat­ing; too quiet makes your snif­fles and sighs painfully au­di­ble to oth­ers, and so is dis­tract­ing. Un­even back­ground noise like traf­fic is worse than the uni­form back­ground noise of white noise or trick­ling wa­ter. Bad back­ground noise leads to poorer cog­ni­tion and fo­cus.

It’s easy to be both­ered by noise and not re­al­ize it un­til the noise stops and a wave of re­lief fi­nally makes you aware of how an­noyed you were by the sound. Noise is­sues are hap­pily easy to con­trol: earplugs or noise-­can­celling head­phones will gen­er­ally do the trick. It would be utopic to elim­i­nate both­er­some noise from the en­vi­ron­ment al­to­geth­er, but it’s not nec­es­sary.

Seg­re­ga­tion of Ac­tiv­i­ties

A heroin ad­dict who nor­mally takes their dose in their car de­cides one day to in­ject in their bath­room. They die of an over­dose, even though they took the same amount they nor­mally do. Why? Our brains main­tain as­so­ci­a­tions with dif­fer­ent en­vi­ron­ments. If you nor­mally in­ject heroin when you get in your car, then your body starts to pre­pare you for the drug as soon as you get in the car. Drug tol­er­ance, then, is partly en­vi­ron­men­tal. (This ac­tu­ally hap­pened and hap­pens reg­u­lar­ly.) Your mind and body are af­fected by your en­vi­ron­ment due to Pavlov­ian con­di­tion­ing. When the bell rings, the dog sali­vates. When the lunch bell rings, so do you.

One com­mon piece of ad­vice given by doc­tors to in­som­ni­acs is to only use your bed for sleep­ing and for sex, and it’s good ad­vice. If you use your bed for read­ing, study­ing, and watch­ing TV, then your mind will not form a strong as­so­ci­a­tion be­tween the bed and sleep, and you will have a harder time falling asleep.

Like­wise, if you do all your slack­ing off at the same desk you do your work at, you will prob­a­bly have a harder time fo­cus­ing. Even hav­ing your smart­phone within your field of view while you work has been shown to re­duce fo­cus. So it would­n’t hurt to have dif­fer­ent ar­eas for work and play, and to not eat at your desk. (And even dif­fer­ent user ac­counts on your com­puter for work and non-­work, if you don’t find that idea to be a pain in the ass like I do.)

We also form as­so­ci­a­tions not just with space, but with time. Hence an­other piece of com­mon sleep hygeine ad­vice: go to sleep at the same time every night. Your body will learn to ex­pect sleep at that time. Like­wise, peo­ple who eat at the same time every day eat with their bod­ies pre­pared to re­ceive food, and so are less likely to be­come obese. Stud­ies have shown this. Un­for­tu­nate­ly, set­ting every as­pect of your life to a clock can make you feel like a ro­bot, so I usu­ally don’t tol­er­ate such rigid­ity in my life. But it’s worth think­ing about.


I also think the aes­thet­ics of most of our in­door en­vi­ron­ments could use an up­grade, but I don’t have much to say on the sub­ject be­sides sim­ply say­ing so. (Though I would bet: green lush > grey drab.)

We some­times act like we are just machinescaffeine in ⟶ code out, but we are not. We’re mushy crea­tures with del­i­cate bod­ies and del­i­cate minds, too. And we evolved for one spe­cific en­vi­ron­ment. There is no guar­an­tee that the in­door en­vi­ron­ment which is cheap­est to pro­duce is go­ing to be just as good for us as a be­spoke im­i­ta­tion of our evo­lu­tion­ary en­vi­ron­ment, and in fact it is not. I think life would be more pleas­ant if peo­ple took these fac­tors more serously when de­sign­ing in­door en­vi­ron­ments, and our work would be more ef­fi­cient and less prone to mis­takes.