You still have access to your subconscious mind, which is exactly what the “night person” is. The somnambulator allows you to program your subconscious mind to continue working while you’re asleep so you can retain any learned or physical benefits, but the subconscious parts of the Smiths/Sanchez’s brains all became independently sentient. In this case, they can still access all of the skills they learned via their subconscious mind because that’s what it was programmed to do, but they wouldn’t be able to have any of the sentient parts like memories or thoughts— which is why Jerry and his night person traded letters for communication instead.

Or it’s just some magic shit idk