I know you think you are helping but you are not. There is nothing worse than someone, who has no understanding of anothers mental health issues, just telling them to 'shake it off' or 'get over it'.

One day maybe, you'll find find yourself suicidal and then you'll understand it's not something you can just get over by 'going for a walk'.

Melatonin has contraindications with many psychiatric drugs, due to it being a serotonin precursor. Hallucinogens can also trigger people with mental health issues into mental breakdowns or crisis. I think sleeping well and biking is great advice, but be careful when recommending drug usage to people already on psychiatric drugs, or just in general.