It is completely disputable. Why did Walker have to manipulate the graph if it wasn't embarrassing? And if you don't believe the 'less sleep is good for you' pa

It is completely disputable. Why did Walker have to manipulate the graph if it wasn't embarrassing? And if you don't believe the 'less sleep is good for you' part of the graph, why do you believe the 'more sleep is good for you' part of the graph?