I wouldn't have think you'd need to wear it while you're sleeping, it's mainly to help offset your weight from putting pressure on the area. Even with a walking boot, your foot will need rest....and since you're unable to rest it like you need to, it will take longer to heal.
I've broken a bone in my foot and had to wear one of those horrible walking boots but not at night. The doctor told me it would be 6 weeks before it healed and it was every bit of that time still with some soreness afterward.
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