Transitions are hard for autistic people, and birthdays can represent significant transitions, especially when they fall on age-numbers that society deems special. I've got one coming up myself, and no, I'm not telling you when it is! It's redacted information, provided on a need-to-know basis only.
Since October last year I have been internalising the age I am going to be because that way it comes as less of a shock on the birthday itself. I've been using this technique for over ten years and it's helped make birthdays less of a stressful event because I have time to get used to the transition on my own terms and at my own pace. I still don't understand the point of the question “how does it feel to be X age?” because it doesn't feel any different in any way. I do ask the question on other people's birthdays though, because it seems to hold meaning for them, and is an accepted standard question to ask.
This post from Autistic Prism Cat was comforting to read and made me question whether I have some PDA in my profile. PDA stands for Pathological Demand Avoidance although within the community we often prefer different words, such as Personal Decision Assertiveness or something less pathologising and negative. There's actually nothing wrong with not doing something you don't want to do – when it's phrased like that others understand a bit more that it's not necessarily a problematic behaviour that must be adjusted or stamped out, but more a case of having very strong feelings about being told what to do. Sometimes, people with a PDA profile struggle to accede to their own demands – PDA is NOT naughtiness.
I'd always thought PDA wasn't part of my neurodivergence, but understanding that there are shades of it within me has helped me understand myself better and manage some of the difficulties that cause problems out in the real world. It's also helped me accept and embrace being assertive which is really useful in setting boundaries and listening/tending to my own needs.
The major factors in my dislike of birthday celebrations is the attention (hearing “Happy Birthday” start up fills me with dread and fixes my face into a rictus grin), the social interaction obligations of thanking people for their birthday messages and the pressure to do A Thing. The standard choices for a Birthday Thing is often something I detest (group meal, rollerskating, a party with games or loud music), and I don't think it's right that I ask people to come and do A Thing that I might enjoy, but which they likely won't want to do, just because it's my birthday. All of these things are “demands”, demands which I try very hard to avoid.
Things I have done to mark my birthday have included going to a garden centre for a jacket potato with my parents, watching a film with a friend at home, or having a fire and a few drinks in the garden with a couple of friends. All these are low key and low stress, and well within the comfort and coping zones. I do recognise that as the first born, my birthday is significant to my mum (perhaps more so than to me) so we do mark the day together in some fashion.
This year I'd like to go to William Morris' house near London. It probably won't be on my birthday weekend, but that's fine. I'd also like to go to an exhibition in Worthing on the subject of gender, and I've booked a solo week away in Wales too. That is my idea of a good 40th celebration. My interests, my terms, my company.