Sleepwishing is a condition where a godchild unknowingly makes wishes in their sleep.
This condition appears to be usually caused by an "unresolved conflict" in his/her subconscious and/or a lack of sleep. The wishes made while in this state, are usually chaotic and/or destructive in nature. Despite being asleep, godparents are still required to grant these wishes. As a result, sleepwishing is considered to be an incredibly dangerous condition.
Despite these wishes being generally random, they can be slightly related to what is causing it. Sometimes the godchild will add a condition to these sleep wishes, preventing them from unwishing it until they resolve the issue.
Sleepwishing made its first appearance in Dream Goat!, when Timmy wished that Chompy the Goat was free. He begins to feel guilty about it, as Vicky was blamed for it and arrested, meanwhile the town believed he was the hero that stopped her. Due to this, he begins to make wishes in his sleep, which Cosmo and Wanda of course have to grant. He tries to avoid making these, by just avoiding sleeping altogether. A few days later, he starts making "sleep wishes" again after dozing off on multiple occasions. This all culminates to where he makes a wish for a gigantic red monster that he can't unwish until he admits to freeing Chompy. This forces Timmy to ultimately admit his guilt in order to stop it.
Sleepwishing made a comeback in the Season 10 episode, Summer Bummer. Chloe begins to "sleep-wish" after deciding to spend her entire summer studying for a government research program, her "inner child" disagrees with this and begins to cause her to "sleep-wish".