iMac goes to sleep repeatedly while trying to export from Adobe Premiere and Media Encoder

Hi there!

Lately my computer is going into sleep mode when I export video content. I start a render and within a minute my iMac goes into sleep mode. I wake it up and it chugs along until it goes to sleep again. This only happens when exporting from Premiere or Media Encoder.

This had happened previously on really large exports of content that was two hours in length.

Now it is happening with every export.

Any ideas on what might be the problem? Thanks!

Machine specs:

iMac (Retina 5K, 27-inch, Late 2014)

4 GHz Quad-Core Intel Core i7

32 GB 1600 MHz DDR3

AMD Radeon R9 M295X 4 GB