Question: I work at a very young start-up company. We have had turn-over rates (mass resignation of staff, thrice) in the past but changes in the system have led to a more a stable employee retention and better technical-skilled employees. We do games, and I don't know with other software fields, but the "[death march](http://arstechnica.com/gaming/2011/05/the-death-march-the-problem-of-crunch-time-in-game-development/)" is quite popular in our field.

My boss believes that the only way for us to catch-up to top companies is to exert more effort, which generally translates to more time working. Hence, we've had a culture of working a lot of hours (we work an average of 65 hours a week, peaking up to 90hours a week).

Our deadlines are either very difficult and sometimes impossible (since the team is pretty young) but our management sets deadlines at the "if people at company X can do this in X days, we can do it too"

I personally believe that raising team efficiency is one of the factors that can help eliminate too much overtime.

I've seen my subordinates/junior staff often not focused enough during the day, but I don't know how to objectively measure this (I've seen questions here relating to KPI's, or key performance indicators).

I'm in a position where I have good relations with my boss (our CEO), the management and the entire team and I believe they're more than willing enough to hear out what I have to say.

How can I approach this in a way that is beneficial for both the staff and the company?

Answer: 
The simple answer is to simply begin working 40 hour work weeks and make sure YOU are efficient for those 40 hours. If you aren't already burned out then the results will become apparent fairly quickly. If you are already burned out then 40 hour weeks probably won't make a difference, so keep working your 60-90 hour work weeks. Keep in mind that if you choose to continue with the long work weeks you'll be looking for a new line of work in the near future and that won't include any careers requiring thinking skills because your body is going to shut down all on its own because you chose not to listen to it.

I really don't understand how people can let themselves be so taken advantage of like your company does to you.
Other replies list why it's a bad idea to work extreme hours. Let me focus on a different aspect instead.

What you're attempting to do is basically a culture transformation.

This is impossible to do without a heavy management sponsorship. You don't just need to *convince* the management. You need to transform them into advocates of this change.

And that won't be easy to do given that they probably believe they are profiting from the current situation.

If you have management sponsorship, the way to go is:

* informing about the new expectations: the management should be involved
* training for the expected behaviors
* controlling the adoption

A culture transformation is difficult enough to do with management sponsorship. Without the sponsorship it's impossible.