By now, we've all read the research, the horror stories, and the comics about how synchronous our workplaces require us to be. Insane numbers of emails, people changing the subject of an email thread instead of starting a new thread, endless slack messages. It's very easy to say what we don't want, but it's much more difficult to define and say what we do want.
Personally, I want a workplace that is accepting of fully asynchronous communication. An organization that embraces the philosophies behind asynchronous work. A company that provides its employees with educational resources and tools for breaking free from synchronous methods and become highly effective in an asynchronous environment. There are so many reasons for these things. In case you aren't aware of the asynchronous movement, read some literature from the founders of Basecamp who have used their company as a testing ground for new ways of running a modern company. Or even better, check out Indestractible – it's a great read that is packed with evidence-based research that points to the demise of modern companies and their individual employees as a result of complete and utter distraction that comes with the demand for synchronous communication. Of course, that is an over simplification, but once you read the book, you'll see that's not far from the whole story.
The time you choose to work should not matter (barring the need for collaboration – which should only be orchestrated by the individuals needing their schedules to align). Assuming it's not urgent, a message should be responded to when you choose to respond; it should not be disruptive to your workday.
If your run a company, let your company be your product. Your employees will produce greatness if you give the product you provide them is great.