Most people say nothing because they are worried about saying the wrong thing. Saying nothing is worse than saying it imperfectly.
Before you start
Pick a private moment with time in it — a drive, a walk, the end of a shift. Not two minutes before a meeting.
Opening
Lead with what you have observed, not what you have concluded.
"I've noticed you've been staying back late and you seem pretty flat. How are you travelling?"
Not "Are you depressed?" and not "You seem fine, are you fine?"
If they brush it off
Accept it, and leave the door open. "Fair enough. I'm around if that changes." Many people need to be asked twice before they answer.
If they open up
Listen more than you talk. You are not there to fix it. Resist the urge to compare it to your own experience or to offer solutions in the first two minutes.
Ask what would help. Then ask whether they have talked to anyone else — a GP, a psychologist, your workplace EAP.
If you are worried about their safety
Ask directly: "Are you thinking about suicide?" Asking does not plant the idea — the evidence on this is clear and consistent. It gives permission to answer honestly.
If the answer is yes, do not leave them alone. Call 000 if there is immediate danger, or the NT Mental Health Line on 1800 682 288.
Afterwards
Follow up in a few days. The check-in that matters most is usually the second one.
If your workplace has an Employee Assistance Program with us, both of you can use it — support for the person doing the supporting is part of what it is for.