This should work:
final CheckBoxPreference autoP = (CheckBoxPreference) getPreferenceManager().findPreference("autoP");
autoP.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
public boolean onPreferenceChange(Preference preference, Object newValue) {
if ((Boolean)newValue == true) {
getActivity().getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}else {
getActivity().getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
}
return true;
}
});