Os Dursleys fechavam a porta às vezes, mas não todas as noites.

Quando Harry estava sendo punido por deixar a jibóia no zoológico, ele considerou se esgueirar até a cozinha para comer alguma coisa, mas sabia que ele teria que esperar que os Dursleys estivessem dormindo primeiro. Isso significaria que era noite, e mesmo que Harry estivesse com problemas, a porta não estava trancada para a noite.

“Uncle Vernon waited until Piers was safely out of the house before starting on Harry. He was so angry he could hardly speak. He managed to say, ‘Go – cupboard – stay – no meals,’ before he collapsed into a chair and Aunt Petunia had to run and get him a large brandy.

*

Harry lay in his dark cupboard much later, wishing he had a watch. He didn’t know what time it was and he couldn’t be sure the Dursleys were asleep yet. Until they were, he couldn’t risk sneaking to the kitchen for some food.”
_{^{- Harry Potter and the Philosopher's Stone, Chapter 2 (The Vanishing Glass)}}

“The Dursleys had received a very angry letter from Harry’s headmistress telling them Harry had been climbing school buildings. But all he’d tried to do (as he shouted at Uncle Vernon through the locked door of his cupboard) was jump behind the big bins outside the kitchen doors. Harry supposed that the wind must have caught him in mid-jump.”
_{^{- Harry Potter and the Philosopher's Stone, Chapter 2 (The Vanishing Glass)}}

Além disso, Harry se pergunta como ele poderia ser um bruxo se os Dursleys pudessem trancá-lo no armário.

“He’d spent his life being clouted by Dudley and bullied by Aunt Petunia and Uncle Vernon; if he was really a wizard, why hadn’t they been turned into warty toads every time they’d tried to lock him in his cupboard?”
_{^{- Harry Potter and the Philosopher's Stone, Chapter 4 (The Keeper of the Keys)}}

A partir disso, fica claro que eles o trancaram várias vezes, já que é a primeira punição que ele pensa.

Quando eles o trancaram o dia todo, ele teve dois intervalos no banheiro.

Uma vez que Vernon Dursley viu o aviso que Harry recebeu e percebeu que Harry não tinha permissão para fazer magia fora da escola, embora estivesse agindo como podia, ficou furioso e trancou Harry em seu quarto o dia todo. Harry foi autorizado a usar o banheiro duas vezes, uma pela manhã e outra à noite.

“He was bearing down on Harry like a great bulldog, all his teeth bared. ‘Well, I’ve got news for you, boy … I’m locking you up … you’re never going back to that school … never … and if you try and magic yourself out – they’ll expel you!’ And laughing like a maniac, he dragged Harry back upstairs.

Uncle Vernon was as bad as his word. The following morning, he paid a man to fit bars on Harry’s window. He himself fitted the cat-flap in the bedroom door, so that small amounts of food could be pushed inside three times a day. They let Harry out to use the bathroom morning and evening. Otherwise, he was locked in his room around the clock.”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 2 (Dobby’s Warning)}}

Ele recebeu duas pausas para o banheiro, mas não está claro se os Dursleys o teriam deixado sair para outro caso ele precisasse. (Eles estavam muito chateados com ele, mas eles também não queriam fazer xixi em qualquer lugar que não deveria estar em sua bela casa limpa.) Harry também não estava sendo alimentado muito nesse ponto, ele pegava um pouco de comida, mas não muito (o que ele teve que dividir entre si e Hedwig), de modo que ele teria menos probabilidade de precisar de viagens adicionais ao banheiro.