Minimize power consumption IR receiver
Assuming an IR remote receiver as used in TV/PVR appliances...

An IR receiver should be continuously-powered if asynchronously-received light pulses are expected...a receiver hobbled by reduced-power cannot detect signals reliably. Choose one that has been designed for low DC-current from its supply.

When no IR light pulses are detected, these devices pull least current from DC supply. Most have a digital output pin that pulls-to-ground when an IR light pulse is detected. An internal large-value pullup resistor idles at logic high.

IR receivers employ internal circuitry that rejects daylight and ambient light. Automatic internal gain-control adapts to IR light pulses of widely-varying amplitude. These AGC circuits might change current draw by a very small amount, not specified in a data sheet.

Serial protocols often employ a pulse preamble. The leading negative-going edge of the very first IR pulse of this preamble should trigger the microcontroller's wake-on-interrupt. The length of this preamble is perhaps long enough that the microcontroller will be fully awake some time after the preamble starts. Wake-up latency varies from microcontroller to microcontroller and is carefully specified in data sheets. Some microcontrollers allow a choice of wake-up methods whose timing varies from short to long, often depending on microcontroller clock start-up times.