1. In sleep mode, the input pin should be set to input pull-up state and can not be set to floating state. 
2. Two methods can be recommended to realize, which is as follows: 
(1).Most Sonix chips have built-in programmable pull-up resistor for I/O port, customers can enable internal pull-up resistor in program. 
For example: enable P1 pull-up resistor 

mov A, #0FFh
mov P1UR, A	; Enable Pull-up resistor by write 1 to P1UR .

(2). For input IO port without pull-up function (for example: sharing with RST input pin), it is proposed to add an external resistor (20Kohm) pulled to VDD. 
In addition, users sometimes ask how to set IO port to save power. In fact, the input or output is the same, as long as the IO port to maintain a fixed state, not suspended, you can reduce the leakage current; of course, this way need external circuit output to determine the state.