Problem with power-down on Atmega 328p

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3

If this works as intended, then I've learned something:

if (currentlyIdle and millis() - lastAction > 20000L) {   
. . .
}

Edit:
Well I found this, so I have learned something:

Operator Keyword for &&

The and operator is the text equivalent of &&. There are two ways to access the and operator in your programs: include the header file iso646.h, or compile with the /Za (Disable language extensions) compiler option.

at https://msdn.microsoft.com/en-us/library/c6s3h5a7.aspx