How do I handle a long gap on my résumé? - 15 weeks in

My résumé shows a gap from a layoff and some health issues. I am not sure how much to explain. What do you say in interviews?

Thanks for writing this out. I went through something close to it 9 months ago, and it got easier once I kept a simple log of every call and form.

I was hired after a 9-month gap. The manager said the skills test mattered more than the dates.