I have a scenario that the android device exchanges data with a FTP server via Roaming service. I hope to make OS enter proper sleep mode by setting WakeLock type during the data transferring because it really has no interaction with enduser. 

I am going through the sleep threads and trying to verifying that what units will be shut down in sleep mode to prevent data sending. So far, no official doc indicates them . 

So , Would you please help to enlighten me on the questions: When Android enters sleep mode , what components will stop working , like WIFI , Data Roaming ? 

Thanks a lot.