Can someone explain me what does this loss curve says? I was training a CNN model on TensorFlow. After a while I came back and saw this loss curve:

The green curve is training loss and the gray one is validation loss. I know that before epoch 394 the model in heavily overfitted, but I have no idea what happened after that.
Also, this is accuracy curves if it helps:

I'm using categorical cross-entropy and this is the model I am using:

and here is link to PhysioNet's challenge which I am working on: https://physionet.org/content/challenge-2017/1.0.0/
Follow this answer from StackOverflow, I think your problem related to the second cases where your loss gets Nan value.
Maybe you should try to use the larger datatype (for example float 16 -&gt; float 32)