One: Know that you are needed and appreciated, even if it seems you are not.
Three: Never say 'pull yourself together' or 'cheer up' unless you're also going to provide detailed, foolproof instructions. (Tough love doesn't work. Turns out that just good old 'love' is enough.)
Four: Appreciate that it is an illness. Things will be said that aren't meant.
Five: Educate yourself. Understand, above all, that what might seem easy to you - going to a shop, for instance - might be an impossible challenge for a depressive.
Six: Don't take anything personally, any more than you would take someone suffering with the flu or chronic fatigue syndrome or srthritis personally. None of this is your fault.
Seven: Be patient. Understand it isn't going to be easy. Depression ebbs and flows and moves up and down. It doesn't stay still. Do not take one happy/bad moment as proof of recovery/relapse. Play the long game.
Eight: Meet them where they are. Ask what you can do. The main thing you can do is just be there.
Nine: Relieve any work/life pressure if that is doable.
Ten: Where possible, don't make the depressive feel weirder than they already feel. Three days on the sofa. Haven't opened the curtains? Crying over difficult decisions like which pair of socks to wear? So what. No biggie. There is no standard normal. Normal is subjective. There are seven billion versions of normal on this planet.
Extracted from Reasons To Stay Alive by Matt Haig (Canongate, £9.99), out now