There are only 3 trains from KL Sentral to Singapore in a day: 9am, 2pm and 11pm. From Singapore - KL, the schedules are: 8.30am, 1.30pm and 10.30pm.
So i bought the night train 11pm to Singapore and it'll take about 8 hours, reaching there at 7am. Perfect! as i can have whole day walking around Singapore.
There are few types of cabins available:
double-decker bunks: Upper deck - RM40 Lower deck - RM46
premium single room: RM200+
Passengers have to arrive 30min before the departure time. Boarding at KL Sentral 2nd floor, Gate B which is beside KFC. It will arrive at Tanjong Pagar mrt station, at the south of Singapore.