Looking at this article
The Man Who Pays His Way: Let sleeping pilots lie ? You're more at risk on the motorway | The Independent
This dates back to 2007 and we are now in 2017, seems the same story everytime and yet nothing is being done to iron out this dangerous situation.
A quote from that article
When a pilot reports for duty, he or she is assumed to be in full control of their faculties. If they are not, then it is their sole responsibility to declare themselves unfit to work. Airlines uniformly say that they would take no action against any pilot saying that they were too tired to work. According to the Balpa survey, one in three said that they would refuse to fly but would fear disciplinary action. A further one in eight said that they would not declare their fatigue out of fear for their job. They say that they are obliged to be more productive than ever, flying up to six sectors a day.
Clearly for reporting fatique you do face disciplinary with initially no support from your union. I hope this case recently restores some form of confidence by holding ALL those to account and not simply brushed aside.