MEGA2560 interrrupts wake from sleep

2560 running at 8Mhz internal clock.

I attached four RISING interrupts which call the same ISR. INT0, INT1, INT4, INT5
(The pins for INT2 and INT3 have I2C devices attached.)

All four interrupts call the ISR when the 2560 is awake but only INT4 and INT5 will wake it up from PWR_DOWN and I need to have INT0 and INT1 be able to.

Is there something that makes these two interrupts different? Could the serial port affect this?

Code wise I'm really only calling these statements:

void sleep()
  attachInterrupt(1, wake, RISING);
  attachInterrupt(5, wake, RISING);

If they all activate the same ISR, why not just bring INT0, INT1, INT4 and INT5 in on the INT4 pin? if you are using a rising interrupt from these four incoming lines, you can tie the four of them together, using diodes if necessary to isolate them from eachother.

That all makes sense and all but this circuit is already finished on a PCB and those pins need to be kept separate for their respective functions. I just overly simplified everything to rule out other factors of the project. One interrupt (INT4) is NAND output of several buttons another is a charge voltage present (INT1) which is what doesn't work. I need to wake the 2560 to do glowey heartbeat things when a charger is connected!