Boss keeps messaging me after work hours, how to handle without offending?

I had a boss like this and what worked was managing expectations early and calmly, not silence which can look like ignoring. I told him I'm fully contactable during work hours and for real emergencies, but that I switch off at night to recharge and perform better, framing it as being more effective, not less committed. Then I lived it consistently, so replies to after-hours non-urgent messages came the next working day. Muting the chat outside work hours helped me stop the anxiety of the pinging. There are new tripartite guidelines in Singapore around switching off after work, so the culture is slowly shifting your way. If it's a whole-company always-on culture and there's zero respect for rest, honestly consider whether it's sustainable for you long term. Your mental health matters more than looking permanently available.

From my experience, boundaries here are set through consistent behaviour more than one dramatic conversation. Start by not replying instantly at night for non-urgent things, respond the next morning instead, so you gently reset the expectation that you're not on call 24/7. For genuinely urgent matters, agree on what 'urgent' means and maybe a separate signal like a call. You can say something positive-framed like 'I want to give your messages proper attention, so I'll action non-urgent items first thing in the morning.' That signals commitment while protecting your evenings. Singapore has tripartite guidelines encouraging respect for rest time, so you're not being unreasonable. If your boss is decent, they'll adjust. If they punish you for having any boundaries at all, that's a bigger red flag about the workplace. Protect your health, burnout helps no one.