The MAD airport-ran lounges take PP yes but they only allow access 4 hours before flight. Previously I've tried to pay for 4 extra hours, stacking with the PP's 4 to get 8 but was told it's not possible.
https://www.aena.es/es/madrid-barajas-adolfo-suarez/servicios-vip/salas-vip/sala-vip-neptuno.html?p=1575033633736
https://www.prioritypass.com/lounges/spain/madrid-barajas/mad2-amnios-lounge
The IB lounges open at 6am, closes midnight, no access on arrival at MAD because your connecting flight is not before 6am.
If you go in town there are overnight churros places but I think the AMS automatic croquette machines are more interesting.
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