Staying FRESH: 12 hour overnight layover at Changi

Hi Travellers,

Im flying from my country to Changi (5 hour flight)

I've a 12 hour layover in Changi from 7PM to 06:30AM from where i fly to another SEA location (about 2.5 hour flight). Travelling economy

I usually don't care about this stuff but I need to arrive at the final location fresh, well rested and clean. Can you recommend what lounges I can use to sleep/ shower. Is sleep not doable without sleeping pods?

I do have multiple priority passes

Happy to update any other details