Sleeping more when sick?

My son has a little cold. He’s slightly stuffed up and he coughs a couple of times a day. It’s obviously not a bad cold, and he still seems in good spirits, but he’s been sleeping more than he usually does. We’ve been dealing with the dreaded 4-month sleep regression for the past month, but he’s slept over 12 hours each night for the past 4 nights. He’s also been taking longer naps lately. Before the sleep regression, he slept 11 hours every night regularly. I’m wondering if this is only because he’s sick, or maybe there’s a chance he’s actually adjusting to his new sleep schedule? I want my baby to feel better, but I’m loving the fact that he’s sleeping better at night.