We've all probably pulled some long days during a hard push on a project at work.  That's a fairly normal occurrence in high tech work right?  However, if you're one of those poor souls that seems to be in a constant death march of long days for months on end, or if you're a workaholic, you may be opening yourself up to some very blue moods. NPR is reporting on a British study that says putting in a lot of overtime is hazardous to your mental health, and can lead to depression.  And it's not only your mental state that could be at risk, the article also states that working too much can have other undesirable effects.

Working long hours also increases the risk of heart disease, and of decline in cognitive function, according to earlier studies by Virtanen that also followed British government employees.

It's just not worth the potential toll to kill yourself putting in a 70 hour week all the time.  If this is you, either reevaluate your priorities, or check out the Dice job board to land a new and more reasonable gig.