I think it is great you are concerned for your sister... however I believe it might be better if she posts a query herself on something like askaboutmoney.com and gives her perspective. She needs to be the one to recognise that she needs advice.
I have left a job in the past due to workload / stress. There are various things to consider before leaving:
- Before doing anything drastic, perhaps she should take a break (holiday) from work, and use the time to firstly relax, and then reflect. I understand that your sister thinks she can't take a break... however if a close family member died in the morning, she'd be able to take days off... similarly if she was struck down with the flu, she'd be off work... and same again for a wedding... so she should push for a break, as the world goes on.
- Never make this type of decision when tired. At least do so after a weekend of rest. Things always look worse when tired, and difficult to make sensible decisions. If she's working long hours, she needs to get a little bit of time to catchup with herself.
- Sometimes the stress is down to one's one approach to work, not the work. Far away fields can be greener... but changing jobs (regardless of the economy) may not resolve the issues. Just moving to a lower paid job, doesn't mean less stress. She needs to understand what are the causes of the stress. Perhaps as others have said this could then be addressed at work - but I believe she needs to identify the problem / solution... not look to work to do this for her.
If she really needs to leave the job, then leave the job. Life goes on. Don't take a 3-month view, take a 10-year view. In 10-years time she'll look back on this period of time from a better situation. Perhaps there will be bumps along the way, paricticularly in the short-term, but things generally work out - particularly with the right attitude.
Also in terms of looking for a job... remember she is only looking for one job... not trying to get a job for everyone. Regardless of the economy there is always one job out there. Her health and well being are most important.
In terms of Social Welfare, if she resigns, then she should just sign-up for social welfare. Where there is a will, there's a way.