punishing hours

興味深い表現を見つけたので取り上げます。

'Grueling' hours at banks in focus after intern death
The widespread culture of long working hours and all-nighters for banking interns has been criticized after the death of a 21-year-old intern last week, with recruiters and human resources groups calling for changes to guidelines and working practices.

Moritz Erhardt collapsed at his London home in Bethnal Green on Thursday, after reportedly working until 6 a.m. for three days in a row at Bank of America Merrill Lynch's (BofA) investment banking division. The cause of death is unknown and some newspapers reported that he suffered from epilepsy.

But in the wake of Erhardt's death, a group that advises graduates lashed out at employers who allow young interns to work punishing hours. In addition, recruitment agencies that deal specifically with interns called for an independent body to support young people working in the finance industry.

注目するのはpunishing hoursです。
きれいに訳すことはできないですが、今回の場合「まるで罰みたいな残業」となるでしょうか。
ネット辞書や手持ちの辞書には載っていませんでしたが、とあるサイトを参考しますと It means very long hours (of work), as if the job was a punishment rather than a jobとありました。Punishing hours? What does it mean? | Yahoo Answers
インターンに行っている私はまだそのような状況下に陥っていないですが、
今後気を付けたいと思います。

http://www.usatoday.com/story/money/business/2013/08/25/moritz-erhardt-london/2693869/