From working from Europe in a global organization a few years ago, it was interesting to see how American colleagues always seem to be projecting the importance of their work and their persona, with an always-on mindset. And it was interesting how emails got answered in the late evening US time zones, with replies that were clearly in the style of "I want you to know that I read your email and am working in the evening", but with no real effort behind the response. And with silly emails like "going away with family on vacation for two days, so I will be reading email less frequently" - dude, why are you checking your emails on a vacation.
Furthermore, US colleagues often seemed obsessed about strengthen their own work position, paranoid about any initiative which may reduce their importance, and generally working relations and politics to make themselves as hard-to-fire as possible. Some people clearly playing their own agenda not really caring about what is right for the company. And creating as little transparency as possible about information they own, making it hard to objectively assess their performance, or replace them with someone else. The kind of person who will do what they are asked, and little else.
In Scandinavia, my experience is we tend to focus on getting sh%# done, and nobody really cares when you do it. In most work environments people are not expected to be always-on, and we embrace the idea that it is good for people to be able to take some weeks vacation once in a while. Plus with public welfare systems - yes, the dreaded "socialism" - you don't have to be overly paranoid about the consequences of losing your job.
One of the most effective tools I have had in terms of time management, is that whenever someone has asked me something with a questionable or unreasonable timeline, I have questioned the time frame and discussed what are actual requirements - and usually there is no problem shifting the timeline to something reasonable. Just because someone asks, that does not mean you have to say yes. There is nothing worse than under-delivering. It is better both for yourself, and for whomever is asking, to push back and find something that works - and then deliver a quality end product. Or some times reducing the scope - someone asks for a big presentation, which you know they may end up changing everything - and you agree on instead making a rough draft and storyline. So you just saved yourself a ton of work, and all it took was 2 minutes of intelligent discussion.
As for changing the culture, I'd say just take a position regarding how and when you plan to work, and let your colleague and peers know. Or at least discuss what is the expectation in terms of work commitments. So they will not be expecting an always-on mindset. In the end, if you keep delivering your stuff, I would think that is what matters.