Kathlyn Anthony of Old Saybrook was released on $100,000 bond following an initial court appearance Monday on a charge of risk of injury to a minor.
The 54-year-old woman was arrested Sunday after an investigation. Police say the boy's sister told school officials that she was tired because she kept getting up at night to let her brother out of his "sleep locker."
Police say the crate was 36 inches by 22 inches, and 30 inches high.
Anthony told police she had been seeking outside help for the boy's behavior. She refused to comment outside court.
Police didn't disclose the boy's age.