Absolutely! As they say, "Laughter is the best medicine", and that goes for emotional turmoil as well.
That said, it is important to understand the quality/quantity of the sorrow. When dealing with your loved ones, be aware of their fragility in the situation. Most everyone deals with emotional distress differently, so sensitivity to the individual is paramount.
Finally, those you care for can be "read" with body language, the level of grief, and flowing tears. Treat each with what you feel to be the proper uplifting assistance, whether it be a grin, a sweet laugh, or an out and out guffaw; engage them with your love.