What are some autistic traits in adults that might not be obvious to others?

[Answered on Quora.com by Inco Gnito]

Speaking for myself. Here are some from the top of my head.
(Disclaimer: Please note that these are my symptoms, people can be autistic and not have these symptoms and have other additional symptoms).

1. Sensory sensitivity.
Sounds:
A noisy environment is hell for me, but if I say something about it, let’s say at work, I get derogatory comments like “you are such a grumpy geezer”. So I have learned not say anything. If it’s noisy at work, I just go home and work. Same thing if I am at a party or a bar where they play loud music, I make up some excuse and leave, because if I stay, I will more or less crash in 2 hours. I never tell people anymore, I have had enough of hearing how “over sensitive” I am…
Light:
Summer is kind if hard for me, because I need to wear sunglasses not to become tired because of all the light, so I constantly get comments insinuating that I wear glasses “all the time” because I try to look cool. I also can’t cope with led spots, which is very annoying since they have become fashionable. They are so annoying it almost hurts, I once quit an assignment as a consultant because they had led spots in the office. There is no idea telling people about it, they always just get annoyed and say things like “how about not being so sensitive all the time”, “You always have something to complain about”, “Why are you so difficult” etc. So, over the years I have learned to keep my mouth shut, so people generally don’t know I have these problems now.
Smells:
If someone has too much cologne or perfume, I have to leave. I have to get out of the line at the grocery store at least once a month and wait for the “stinky” person to leave and for the smell to disappear. If I don’t do this I will get a headache from hell that will last 2–3 hours. I also can’t stand people who smells of sweat, or have damp smelling clothes. It makes me physically nauseous. If someone has one of those air fresheners with fragrance I can’t stay in that apartment for longer than a few minutes or I will get overwhelmed and even might get a headache.
Touch:
In daily life when someone is touching me, like when I am shoulder to shoulder with someone on the bus, it is like some one is constantly talking right in my ear saying, “Someone is touching you, someone is touching you, someone is touching you, someone is touching you, someone is touching you,…”. Snuggling up together on the couch? That might be nice for 5–10 minutes, but then it is enough or I won’t have a clue what is happening in the movie.
2. More or less constant anxiety.
3. Problems with transitions, like stop doing what I am doing and getting on with a new thing, it takes an unreasonable amount of time and every time it cause anxiety. Getting into the shower, getting out of the shower, getting out of bed, getting into bed. Leaving home for work, leaving work for home. This problem is really time consuming, and probably what affects my life the most negatively of all the traits I have. It is a huge problem at work if I get something thrown into my lap I hadn't planned to do. My starting strip is long, then getting back to what I did takes time. Even a 10 second phone call for from a salesman can set me back 15 minutes. I REALLY hate Coffee breaks at work, first it is hard to stop working, then it is hard to end the coffee break. So while other lose 5–10 minutes of working time, I will lose double the amount and get anxious at the same time.
4. Unable to focus on anything when something else is planned later in the day.
5. Hidden stimming and ticks. I do a numerous of things others can’t se, because I learned to hide these things from a an early age not get bullied or teased.
6. I avoid a lot social events because they are exhausting to me, like AW… But I make up excuses. Generally people think I don’t want to hang out with them, they just don’t get or know that hanging out with more than 4–5 people at a time is pure torture for me. If you tell people about it, you get labeled as antisocial or boring, so I don’t.
7. Being totally exhausted after a 2-hour trip to the mall. Need to sleep 1–2 hours when I get home.
8. Needing much more sleep and rest than others because I get tired from being overwhelmed by either sensory input, too many things going on or social interaction. I sleep about 9 hours on average, very often a 1,5 hour nap in the middle of the day.
9. I am more or less allergic to surprises :) Even if I know in advance one is coming. If people invite me to go out for food and they say the location is a surprise, I will probably not go because of the anxiety it causes.
10. Anxiety and storming emotions inside when people don’t do things in an orderly fashion, or do them sloppy. For example I hate ordering in bars because there is no clear way in which order the bartender is taking orders and people generally just try to get ahead. Continue with bar theme: When the bartender spill beer or let the foam float over the top so that it’s beer outside the glass, I get anxious by those kinds of things, I mean ANXIOUS, and I have to take a napkin and dry the glass. It’s not like feeling a little annoyed, it is really upsetting, and I can’t distract my mind from it, so I really don’t do well around people that are sloppy, and that is quite socially limiting.
11. I get double hangovers from parties. :) First the alcohol but also the exhaustion from socially interacting for too many hours with too many people. There is a huge difference with my “hangover” if I am at home with one friend and drink, or if I am attending an event with lots of people.
12. About 2–3 times month on average I have to take a half day or an entire day off because I am overwhelmed by something. Once or twice a year it can be 2 days off, and the reason it is usually too many things going on in my life. I always save vacation time to make sure I am able to do this. A few times I have had to take an entire week off to just reset and get my thoughts and emotions into order. It has become less of a problem as I’m getting older because I have become better at managing myself. I know my limits. I usually excuse myself with having an errand, because if I tell people I need to sleep for 4 hours or just space out for a day or two to recover they always assume I am sloppy with sleep or that I am depressed or having a mental breakdown.
13. When writing posts like this, I am never satisfied with it and can get back to it 10–20 times to reedit… I did that with this one. LoL. But now I will stop…. Honestly! :)
14. Every time I have to drive to some place I haven’t been or use public transportation for an appointment I will be super anxious and I need to REALLY plan how to get there. I will start days ahead. I have to know exactly where to park, or exactly when bus or train is leaving and how long I will wait at each stop etc. If I drive I will start driving at least 1 hour too soon to be sure I will get there on time and have time for anything unexpected. To get rid of the anxiousness I plan any small little trip like I am going to the other side of the globe.
15. Very unreliable but otherwise exceptionally good memory. I temporally forget common words, all the time, and have to rephrase what I am saying, so people don’t notice. When at home, like doing chores, I constantly forget what I am doing, and I have to pause and use my mind to walk back and ask myself why I walked into this room, that works, so I can always recall. I can temporarily forget how to drive somewhere I have been to 30 times. I work IT, and I can suddenly forget a command I have used for 20 years, so I have to google it. I can even hesitate and forget my kids names for a short while. I constantly forget my phone number even though I have had it for 20 years. Now you might say, that sounds like early dementia, and that might be true, but then I have had early dementia since I was a kid… :) My memory works best if I am alone and tend to fail the most if another person ask me something IRL eye to an eye.
16. I am not a “team player” and never will be, not because I am egoistic or doesn’t want to, but because I function at least 300% better when I work alone.

Edit: Added bullet 17, 18 on 11th July 2023
17. ADD (sub diagnosis of ADHD). It is so common that that the scientific community are leaning towards including it into the Autistic spectrum.
18. Pathological Demand Avoidance, or PDA. Not necessary part of the autistic spectrum even though new research is leaning towards that. This means it is very hard for me to do things I “have to do”. Scheduling the day is like kryptonite to my productivity. I get anxious starting and doing “musts”, unlike other people who usually get calmer by ticking off todos. For me it causes anxiety. It is like I am not in control and have to do things because of external demands, hard to explain. The actual act of doing something I have to do makes me anxious while I am doing it.

Even worse if something happens that is unplanned, like a broken window at home. I can’t deal with it right away. It is like I can’t accept random things happening, so I can’t deal with it. I have to wait for it to sink in a few days, sometimes more time and sometimes just a few hours. So, even if it is just a phone call to a carpenter, I will first put duct tape on it and then call in the carpenter in a few days. Of course these kind of things can drive people around me crazy, and they think I am lazy, but I am really not. I think my last relationship (with my wife) crashed mainly just because of this, because she would get angry and do it herself, and ended up bitter over that “she had to do everything”, it is just that she didn’t have the patience to wait (I don’t blame her, really). People around me think it is classical procrastination, but it is not, I also procrastinate sometimes, but that is an entirely different feeling, and eventually I will do the tasks, unless they stagger up… Then I get totally overwhelmed and need a 1 or 2 days to do nothing at all. So I don’t respond well to external pressure... :) So I like doing things well in advance, which I get teased for. Like buying Christmas gifts in July… If I do something that isn’t a must, even if it is boring, I can work 16h-days… Ex: I studied german in school, and I sucked, I hated it. But when I got out of school and there was not pressure, it became a hobby and I learned it in 1–2 years. I also learned python programming language in my spare time, but when it was obligatory at the university I failed the class.

Generally my autism is quite hidden, even though I am close to lvl2, people do not know I am autistic even though almost everyone finds me a bit “quirky”. I am VERY good at masking (too good for my own sake) and have learned how to not get noticed for “the wrong reasons” the hard way. But I have real issues that I struggle with quite hard on a daily basis. I found this question interesting because I know many “normies” do not really understand that a person can be quite far into the spectrum without anyone actually noticing. So maybe this answer might raise some awareness so people might stop skeptically stating things like “well, everyone is a bit autistic” when people like me reveal they have a diagnosis. The struggle is quite real even though it might be invisible for most people.

This all sounds quite negative, a bit of nagging really…. so, anyway… by overall I wouldn’t want to take my autism away, because it has given me a very good and comfortable life. It have blessed me with a very high cognitive ability, which has served me well with school, hobby and career. I am never bored. I can have fun for hours alone just thinking about and maybe solving philosophical, political problems or likewise. I can have fun on a plane for hours with no phone, just being alone with my thoughts. So I am not even afraid to become poor. All I need to be happy and content is access to books, a bed and pen and paper and maybe a computer. Most of my problems with autism is how the normie society and normies constantly expect me to be like them and try to force my arm in order to be like them. And when I don’t act accordingly I get punished. So generally, I avoid “normal people” and “the normal society”.