Set your Power Settings to Sleep - Never.
MPI processes are typically run on servers - IOW they never sleep.
You also have a similar issue with non-MPI processes on a single system where when (if) the system goes into sleep mode, the application is suspended. Should this application have, as an example, a socket open to a FTP server, the server may terminate the connection and/or transfer that was interrupted. The work around for this is to set your Power Settings to Sleep - Never.
Note, you can research (google) for programmable way to modify the system Power Settings, then construct a thread-safe (multiple process safe) means to modify the power settings (e.g. have a count of the number of processes desiring Sleep=Never.