Thank you all for your advice.
Last night they seemed to have higher spirits and it's encouraging to see them with a smile on their face and being a bit more talkative. But now they've found out that the company they work for has gone into receivership but they haven't been made redundant as yet. They've never been happy with their job and I think this may have aleviated some stress in a strange way.
Thanks again for all of your advice, I was finding it difficult to cope with and felt helpless but in perspective I'm fortunate not to be the one suffering the depression.