Bridge Load Limit

“I try to take one day at a time, but sometimes several days attack me at once.”
~Jennifer Unlimited


Sometimes it’s hard to explain why things get overwhelming, or why something I could tolerate just find one day becomes overwhelming on another day. I look “normal”. I earned university degrees, hold jobs, have a family, converse like an intelligent person … and then I’m standing there dumbly like a deer in the headlights, or am staggering down the hallway flapping a hand, or am seated away from others and rocking in agitation. I’ve turned into a “not-normal” person, and transgressed that invisible boundary marking staff from students / clients, or have shifted from upstanding citizen to crazy-looking person on the street.

Amanda wrote a pithy blogpost on 6th May, 2006, making the excellent point that what constitutes a sensory overload threshold for one (autistic) person may be quite different for another. This is relevant to all sorts of types of inner and outer functioning; as she points out,

This isn’t meant to be one of those vacuous statements about looking at how fortunate you are in comparison to someone else. It’s more the opposite. I can see a potential for auties to say, “Well I never had that, so losing it isn’t a big deal, I live without it all the time.” And I keep thinking “No, this is one of those things that really is relative to how someone is doing normally. For some people, losing the ability to talk signals a big crash, for other people it is commonplace. The fact that it’s commonplace for some of us does not negate the fact that it signals a big crash for others.”

What many people don’t seem to understand is why some kinds of environments are overwhelming.

Even when the explanations are couched in terms that “anyone” (meaning most neurotypical people) can relate to, and prompt the inevitable they-almost-get-it responses like, “Oh yeah, I’ve had days when I couldn’t stand to be at Chuck E. Cheese for another hour,” (that place being one of those horribly noisy, busy party establishments full of children’s carnival games and mediocre pizza). What is then puzzling to others seems to be the inconsistency of responses in the stressed person (autistic or otherwise). That is, the next time around one gets the annoyed comment of, “Well, you handled this just fine last time, so I don’t see why you’re wanting to leave right after we just got here!”

Nevermind that “just fine” last time meant becoming withdrawn and less sociable, rather than spending unusually long amounts of time cloistered in a bathroom stall, or staring blankly at the floor, or having to outright make a U-turn and depart. People’s responses to stress differ from one person to the next. A person may strike out, flee, or become withdrawn. Parents of toddlers are familiar with this, and will watch their tots so they know when it’s time to take a break. Of course, everyone expects that an adult should be able to deal with everyday life. Most people can in their everyday situations – it’s when life surpasses the invisible and seemingly inexplicable thresholds that coping abilities are exceeded.

What many people don’t seem to understand is why some kinds of environments are overwhelming for some people.

Frankly, not everyone has the same thresholds for the same things. It’s egocentric to judge everyone else by one’s own ability to tolerate things, and yet millions of people do it, “It doesn’t bother me, so I don’t know why she has to be so ‘special’.”

What most people don’t realise is that we don’t all experience the same world. The external, physical world for everyone is the same, but our sensory perceptions and perceptual processing are all individual. A moment’s thought will generate the realisation that a terribly bright, sunny day isn’t going to bother a blind person the same way as most people, but it is less obvious that such a day will still be excruciating for people with some kinds of vision impairments, or even for others who are simply more sensitive to ultraviolet rays. Or for example, one of my professors could not understand why I found a lab environment “so noisy”. It wasn’t until a couple of years later that we realised that for all he had sufficiently good hearing, he could not hear all the high-frequency noises that I could – my subjective sensory world or “Umwelt” was different to his. Nonetheless, because he did not find it noisy, by his definition it “wasn’t noisy”, and therefore he felt that it wasn’t sensible for me to complain that all the laboratory machinery gave me headaches.

What many people don’t seem to understand is why some kinds of environments are overwhelming at some times but not others.

Our thresholds are variable by our entry level status before those inputs. In other words, how well one copes depends upon how the day has gone beforehand. This important point about these differences between baseline and reaction levels is like saying that ice cream melts quicker on a hot day than on a cold day. (As friends in Finland say, Siis niinku, Dah!) Like many important points, it’s obvious in retrospect. It’s not just the (1) novelty and (2) complexity of the sensory inputs, or the (3) frequency, (4) intensity and (5) duration of the experience, but also (6) how much energy one has stockpiled or already spent during the day before even reaching that situation.

Baseline stress loads matter and thresholds matter. In her fascinating and surprisingly humorous book about intractable pain that has lasted for over a decade, All In My Head: an epic quest to cure an unrelenting, totally unreasonable, and only slightly enlightening headache Paula Kamen describes her approach for budgeting energy as having a limited number of “daily marbles” to spend. Christine Miserandino has a similar analogy for dealing with lupus (and similar debilitating conditions) in her Spoon Theory. So, if a person gets to lunch time and has already spent most of their daily “marbles” or “spoons”, an experience is going to be much more overwhelming than it would be otherwise.

In the same regard, everyone has different tolerances for different kinds of inputs, and those tolerances will differ by these same six variables. Day-care workers handle screaming children for hours. Professional proofreaders deal with blinding amounts of text. Bartenders specialise in chit-chat as well as mixology. To do these jobs well, each worker needs a high tolerance for specific kinds of input. On any given day, any one of them will deal with their related stresses better or worse, depending upon other internal and external circumstances. It would also not be surprising to find one professional telling another, “I could never do your job – I just couldn’t deal [with it]!”

Given that individuals are unique, it helps to remember that it’s neither necessary nor beneficial to hold everyone to some imaginary and unrealistic ideal of what everyone “should” be able to tolerate in daily life. Over the years my husband has come to understand that my pain and gore thresholds are way higher than his, but that my social chit-chat threshold is way lower.

Now, I need to go remove several hundred weeds. I used to do that, then all the mowing and flower dead-heading, followed by housekeeping and cooking dinner. Nowadays I know that although I could do that if I had to, it would leave me wracked with joint aches that night and the next day. I have learned to mete out my challenges simply as a matter of common sense — “I could do all these things, but I choose not to because it would invoke too much stress.” Avoiding meltdowns or physical self-abuse by over-work are perfectly sensible goals!


Also known as, “What in the world is so bloody over-whelming, anyway?”

Natural environments, even visually complex ones like forests or prairies are okay — they have an order to them. There is a limited number of visual textures, of weather-plant-animal sounds, of weather-plant-animal-mineral smells. More importantly, it is easy to distinguish the relative importance of sights, sounds and smells — I know to which I need to pay attention. The inputs rarely change drastically from day to day, aside from a sudden snowfall or prairie burn (which actually decomplexify the inputs).

It’s the artificial environments that I have trouble with. Cluttered rooms, chaotic places like shopping malls, or new places I have not been to (be they offices, transit stations, or stores) are problematic. I can tell things apart and more or less navigate okay, but I have trouble sorting everything — I notice some details all out of proportion to others, such as the minute details of chair upholstery weave instead of important signs on doors.

Some details I cannot “see” at first, until I have had time to sort everything. A store that has been drastically re-arranged means I will spend three times as long trying to find the toilet paper. I may end up wandering around so long tracking down the toilet paper, I forget what else it was I was looking for. Today I took my daughter grocery shopping at a market where we had never shopped. Because she was the one concentrating on what items needed to be purchased, I could focus my attentions upon navigating through the store aisles and around the other shoppers, and finding the necessary items. Seriously, finding those items was no small challenge, as neither of us were familiar with the particulars of the layout, nor understood how that store’s stock manager had chosen to organise some of the products (we never did find the frozen chicken).

If you have ever travelled in a foreign country where none of the grocery packages or labels were your familiar brands, where they did not come in the same kind of packaging, and where they were not printed in your own language, you have some sense of the queasy, almost cross-eyed bewilderment I feel.

I’m that person who exits the jetway and stands dumbly in the middle of the airport hallway for a couple of minutes as I visually sort and mentally map my surroundings. It’s a bit like putting a photo wheel into a View-Master stereo-opticon crooked, or having your glasses frames horribly bent, and your two (binocular) views are not in perfect registration: the focus and perspective are all skewed. Once I have sorted things out in my head, this is like adjusting the picture wheel, and pop! everything is finally in focus.

In a familiar environment, you have learned which inputs are important, and which can be ignored. In the unfamiliar environments (railstation, shopping mall, new school, strange city) you are bombarded by many new inputs. But even in the familiar environment, sometimes the sensory input is too high, and this is a stressor.

In addition to the environmental stress, there is also the interpersonal and intrapersonal stresses because others do not think this “should” be a problem, and therefore do not take your problem seriously.

Let’s walk around school, and a city block to discover what things are in a typical environment …


  • rooftop antennas shrieking in the wind
  • snapping flags and clanking flag cables
  • shrill cacophony of playground swings resonating down the pipes
  • thrumming power lines
  • buzzing fluorescent lights
  • humming CRTs
  • whining disk drives
  • huffing printers
  • snickering electrical switchboxes
  • ticking or pulsed fizzing of clocks
  • strident jangling of class bells echoing down tiled hallways
  • steam heat hissing and thumping and clanking
  • air conditioners with shrill fans and grating motors and drip’drip’dripping pans
  • thumping compressors
  • throbbing condensers
  • cavernous reverberation and intense whirring of elevators
  • water pipes gurgling and clattering
  • whining roar of hand dryers
  • squeaking sneakers and clattering heels and clomping boots and slapping flip-flops (sandals)
  • swishy corduroy and nylon pants
  • squishy gum chewing and snapping and candy rattling between teeth
  • scritchy chalk and squeaking markers and grating pencils
  • din of multiple conversations and yelling and piercing shrieks
  • tinny radios
  • blaring televisions
  • raucous cell phones
  • sibilant headphones
  • slamming or squeaking doors
  • rattling door windows
  • leaky window jambs that moan in the wind
  • sputtering coffeemakers
  • beeping microwaves with aging discordant mechanisms
  • vehicle engines and gears and brakes
  • horn honking and wailing sirens
  • screaming jets and sputtering turboprops and chuddering helicopters
  • squawking and whistling and chirping birds
  • chattering squirrels and the scrabbling of their claws up and down the tree bark
  • strangled murmuring of pigeons
  • buzzing and skittering and droning insects;


  • deep tang of hot wet asphalt
  • acrid ammonia of anaerobic rotting vegetation stuck up in gutters
  • rank heavy sweetness of pesticides and herbicides
  • competing old fry fat and char of multiple fast food sources
  • flat bitterness of over-simmered coffee and penetrating singe of microwave popcorn
  • comforting crispness of fresh newsprint
  • stale sour body odors compounded with the intrusive artificiality of perfumes, aftershave, scented deodorant, cloying fabric softener, and hairspray
  • chewing gum and mints and candies
  • nauseating sting of cigarettes
  • playful funk of dogs
  • bouyant mellowness of floor wax
  • abrasively floral room “deodoriser”
  • caustic bathroom sanitizers
  • various toileting odors including the muddy smell of used tampons & maxipads, and the sharp sour odor of someone with intestinal upset, and/or ketosis odor of someone on a high-protein diet
  • institutional handwashing soap and brown paper towels
  • trenchant skunkiness of locker rooms
  • mustiness of wet leather shoes
  • sneezy chalkdust
  • dizzying whiteboard marker
  • hot photocopier toner
  • coziness of singed dust in the heating system
  • pungent chewiness of hot roofing tar
  • itchy green juiciness of freshly mown grass and turf weeds
  • suffocating car and diesel exhaust
  • heady fascination of spilled gasoline (petrol)
  • miasma of combusted engine oil
  • foul stickiness of garbage bins;

(I might add that when I am in educational environments, I do not wear any scented body products, to avoid bothering people who may have olfactory sensitivities.)


  • people, cars, trucks, bicycles, motorcycles
  • buildings, windows, doors, railings, gutters
  • shop signs flags, awnings, shutters, balconies, window air conditioning units
  • café tables and chairs, railings, gates, doormats
  • trash, graffiti
  • streetlights, fire hydrants
  • bicycle racks, mailboxes, newspaper bins, trash cans (rubbish bins)
  • utility posts, traffic signals, traffic signs, street signs
  • storm grates, puddles, sewer access covers, curbs (kerbs)
  • floors-stairs-lights-elevators (lifts)-escalators
  • exit signs, building/room numbers
  • landscaping plants, directional signs, advertising signs and so on (there is a LOT of signage in the world!)

At worst, there is no filtering, no prioritizing, no discrimination. Everything is experienced all at once, even those details that most people are not even aware of or cannot perceive. Each item has to be identified and sorted. So what results is that either I am standing there blinking, overwhelmed and processing all the stimuli to make sense of it. If the inputs are too much or my tolerances are too low, then I am trying to block out some of the stimuli by staring at the ground, and trying to re-regulate my internal stress by rocking.

These “stereotypies” of rocking or bit of hand-flapping are both signs of stress and ways of reducing stress. I really don’t believe that trying to make people look “normal” or “indistinguishable from their peers” by suppressing or forcefully training out such coping mechanisms is a good thing. The social stigmatising and the training methods can be additional stresses, and removing a stress-release mechanism from someone’s toolbox of life skills is simply going to result in their finding a different behavior to serve the same function. Although some other behaviors may be “more acceptable” (who gets to decide these things, anyway?), there are plenty of maladaptive behaviors out there that we want to avoid, e.g. chemical dependency, self-injury, overt or passive aggression, et cetera.

The real “problem” with stereotypies is that not that people do them, but that others have hang-ups about actions that harm no-one. (In analogy, the problem with racism is not that someone has phenotypic characteristics to their “race”, but that others are bigoted.) It is disrespectful and demonstrates a distinct lack of empathy to hold everyone to these artificial and unrealistic ideals of what everyone “should” be able to tolerate in daily life. Furthermore, it is stupid to deprive a person of their coping methods, and then complain because the person isn’t coping and has a melt-down or shut-down!


  1. Mados said,

    24 February 2012 at 5:21

    In addition to the environmental stress, there is also the interpersonal and intrapersonal stresses because others do not think this “should” be a problem, and therefore do not take your problem seriously.

    I agree. This is why I don’t go to malls, rarely go to parties (usually only when I know the place and have a retreat/escape plan) and avoid shopping in super markets as much as I can.

    Yesterday I did shop in a supermarket where I have never been before. I had to because we just moved to a new area and was out of everything including toilet paper, salt, oil, bread e.t.c. My husband is overseas, he actually usually does most of the shopping.

    It took ages to find what I needed to buy, I felt lost and disorientated and a repetitive loud beeping sound frequently started and tore through the shop for several minutes for whatever reason. I wore ear plugs but they didn’t reduce the noise to a tolerable level (albeit less painful than without them). I eventually rushed out with about 1/2 the things I needed and felt like I had been tortured for hours. Drained the rest of the day, which is a pity because I had something on for the evening that’s a high priority for me (music practice).

    This is why I avoid distressing environment, I don’t fight to ‘try to overcome’ my reactions anymore because it never worked and never will. People who see me in my confused mode may think I am ‘stupid’, slow, unfriendly, snappy, numb, make lots of mistakes; may at best subtly judge me for my behaviour and ‘vibe’. I’ll end up drained for (typically) the rest of the day, on edge and irritable or sad, and have minimised my chance to achieve much of value that day; because I don’t have the focus and energy. Nobody thank me for enduring a nightmare; because what I have done is just ordinary. They may however blame me for the effect on me of doing it.

    Enduring stressing environments is not worth the objectives of living up to expectations e.t.c. In this case I got toilet paper which I needed of course, but it was way to expensive in opportunity costs (spending all my mental energy).

    • Mados said,

      24 February 2012 at 6:55

      Hope this didn’t sound too whining… it wasn’t my intention to whinge, of course shopping is something that everybody have to put up with.

      Just for the record, I am not autistic (as far as I know). I do have some major issues that seem similar to typical traits and symptoms of the Asperger symptoms, which is why I read about it. But not all of them.

  2. Mados said,

    24 February 2012 at 4:22

    What most people don’t realise is that we don’t all experience the same world.

    Very true. I also recognise your professor’s attitude, I have met if often. ‘but it is not noisy. Why do you think it’s noisy?’

    – and inconsistent thresholds: Like ‘I thought you didn’t like noise!?’ if I listen to a street percussion band in awe… (I love percussion music)

    I do like sounds… I just don’t like to drown in a confusing chaos of irrelevant, uncoordinated noises. I like sound patterns, I just don’t like sound fragments. I also don’t like painful sounds (high pitched whistles, beeps e.t.c) and I don’t like multiplied, distorted sounds such as noise inside malls, halls / reverberate indoor places where each sound has multiple distorted echoes coming from different directions; greatly multiplying the total amount of meaningless, confusing noise. I like noise much better outdoor where most sounds have only one version, and then disappear.

    Also in malls and supermarkets there is the added confusion of visual clutter and disorientation (well… having to find things). Your description is very spot on. Also that it is the total amount of inputs and demands that determines the tolerance, including earlier stresses, ‘marbles spent already’ and the energy level of the day.

  3. 19 April 2009 at 18:49

    […] combined effects of all the daily noises, the “life in surround-sound” as described in “Bridge Load Limit”.  As I’ve described before, hyperacussis is a “super-power” that truly, truly […]

  4. EstherForever said,

    10 August 2007 at 15:52

    Awesome, insightful post. Perhaps I’m not autistic (although afew friends and my spouse and I agree I display a suspiciously high number of “traits” not to be…), but my son is. Speaking first as a mom, I can’t tell you how comforting, how helpful it is to come in here and be able…be allowed…to read your thoughts…your challenges. Its probably as close to getting into my precious little boy’s head as I may ever get…at least for now. God bless you…God bless you for sharing and allowing us this chance to do what any loving, compassionate mother of ANY child would want…to do everything in my power to reach into my son’s “world”, to share it with him, to do all that I can to make his life less stressful…by understanding why he rocks, why he only eats 4 foods, why he obsesses to the noise of the vacume cleaner…etc. etc.

  5. Esther said,

    10 August 2007 at 15:36

    This is my first time in here! Bravo…loved your post!

  6. qw88nb88 said,

    17 July 2007 at 0:37

    Ooh, sorry ’bout that Bev! It wasn’t meant to be quite that vivid …

  7. Bev said,

    17 July 2007 at 0:23

    You are such a good descriptive writer! The sections on sound and smell both made me feel sick. Literally sick. Impressive…

  8. andrea said,

    16 July 2007 at 12:21

    I keep earplugs along with my sunglasses clips in my purse. Earplugs don’t even begin to drown out the sound (I’m hyperacussic), but they do muffle it to a more tolerable level. I also have a nice scrap of chamois that is useful not only for cleaning lenses, but also gives me a familiar “fidget widget” to focus upon.

  9. Ms. Clark said,

    16 July 2007 at 7:21

    Thanks, again, Andrea. It’s a great post. I can’t believe you came up with so many original and apt descriptions of odors and sounds….

    I could never live in a city… oy… the smells in subways are just icky to me, and the sounds are almost torture. BART doesn’t smell bad, but some of the noises are torture. I have to cover my ears to cope. It’s hard to look “cool” when one is hunched over covering ones ears, intermittently. Oh, well. Next time I’ll wear a tiara and see if it balances out the uncoolness of the ear covering… :-)

  10. 16 July 2007 at 2:40

    I actually find just about any visual stimulus overloading. (Which is why I wear tinted glasses all the time.) It’s like just the act of looking at things is painful, looking at them for meaning is worse.

  11. Bug Girl said,

    16 July 2007 at 2:16

    This is a wonderful post. I am going to bookmark it immediately and send it to some folks who don’t “get” it.

    Thank you for writing it.

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