Doubt about Sleep Mode

Hi,
I'm using official Arduino Uno/Genuino

I have a question about sleep mode:

I've an interruption which on when a pin changes low to high.

I put the arduino in IDLE sleep mode.

After the interruption, will arduino sleep again automatic and wake up when the sleep time ends?

You should mention what microcontroller (which arduino board, or which chip if using standalone) when asking a question. There are over a dozen official boards spanning at least three architectures, dozens of AVR's used standalone, and other third party board packages. A few of these are weird, and there are specific comments we might make depending on what you're working with.

Generally, after the interrupt that woke the chip finishes running, execution of code will continue from immediately after the point where you put the chip to sleep. It's not uncommon for the ISR to be empty when it's just being used to wake from sleep.

DrAzzy:
You should mention what microcontroller (which arduino board, or which chip if using standalone) when asking a question. There are over a dozen official boards spanning at least three architectures, dozens of AVR's used standalone, and other third party board packages. A few of these are weird, and there are specific comments we might make depending on what you're working with.

Generally, after the interrupt that woke the chip finishes running, execution of code will continue from immediately after the point where you put the chip to sleep. It's not uncommon for the ISR to be empty when it's just being used to wake from sleep.

Ok , thanks! I'm using offical Arduino Uno/Genuino, so if i want to sleep it again the rest of the period i'll have to save the time has run.

Ah, okay so it’s an AVR.

You don’t save that much power in IDLE - you can get it a lot lower with POWER DOWN sleep mode (be sure to turn off the ADC too) - but in that case, you would have to switch to using a PCINT to wake it, since the rising/falling trigger options for “external interrupts” don’t work to wake from sleep… while PCINTs do.

Study this great tutorial on sleep modes and power saving.

Sleep mode reduces consumption on Arduino Uno but there are many other power hungry parts: to get rral power saving you need standalone chip (or another board).
Sleep is not resumed after ISR: the code continues after the command that put the chip into sleep.