I have developed a few autoimmune conditions in adulthood, too. Thank you for your understanding, and yes, you're right, by the time the school holidays came around I was so tired, but I wasn't allowed to sleep or even nap as my brother, from straight after breakfast until sundown had to be occupied.
My mother said that the day I turned 18, I changed overnight, but the reason was, I was tired of having to occupy my brother. I remember one Wednesday morning, not long after I turned 18, when I wanted a relaxing day, my mother told me, even though she KNEW I damn well HATED it, to go and ask my brother if he wanted to play cricket. Talk about forced masking!