You could take a look at Jack Christensens sleep code for the ATtiny85.
http://forum.arduino.cc/index.php?topic=167467.0
I have used it with this core without issues:
You could take a look at Jack Christensens sleep code for the ATtiny85.
http://forum.arduino.cc/index.php?topic=167467.0
I have used it with this core without issues: