I'm not familiar with the EU regulations but in our lab (in Canada) the girls work various shifts up to 2330, after that they are on call. Call ends at 0700 when the dayshift arrives, the on call person does not return to work until 1530 giving them 8.5 hours off. On the weekend we work a 12 hours day 0700-1900 and then take call for 12 hours. Potentially staff can work all night on call Saturday and then have to be back to work for 0700 Sunday and then back on call for Sunday night. This isn't normally an issue as we may get 0-3 calls/week, I think that if it were a problem then you would be looking to staff the shift.
