I have a really sweet dog who can be shy when she first meets people. She’s good with my kids and their friends if we do nice introductions at the door. I ask the kids to stand still and let her sniff their hands. She usually comes over to check them out and then is fine with them being in the house.
But when we have a sleepover, she sometimes barks at them after they change into their pajamas! Why does she do that? What could be scary about pajamas? ~ Kathleen
It’s not so much that she’s reacting to pajamas, but that she’s reacting to change. Shy dogs tend to be very attuned to their environment and immediately notice when things change. Because shy dogs tend to worry, they often respond to something new as if it were something bad.
When you have kids stay over, keep her near you while they go change and then have them come back over for a quick reintroduction. It sounds like she just needs your support to help her understand that, although their clothing changed, the kids remain the same. This will be much easier for her if you take the time to do introductions once again.