We try to do it every couple of months with our down pillows because, somehow, it makes our bed feel that much more comfy and clean. According to our family, the sun is a natural disinfectant and just being outside, the pillows are spruced up, cleaned up and fluffed up.
It's something we'd like to do every month, but we're human and we forget, but we definitely do it after we've been sick (in addition, of course, to washing our sheets). But especially living in Southern California where we get so much sun it's easy to just put an old sheet out on the ground and plop our pillows down to hang out (on each side) for about 30 minutes in direct sunlight. Sometimes we really indulge and will leave them out there all day. This might not have any real effect, but it's something mom and gramma taught us to do and we think there's real wisdom in that.
Is this something you do?