How is this possible? Too little sleep?

Get a physical every year. Work out regularly, even if it’s just a walk a couple times a day. If your company is pushing you to the breaking point, quit. Someone else will be hired and they’ll reach the same point and hopefully quit too. Don’t let multi-trillion dollar whathaveyoudoneformelately corporations ruin your life.

There is always a sword of Damocles hovering over everyone's heads to pressure workers to overwork day and night.

Overworking long hours on someone else's terms and management doesn't care as they'll replace anyone with another worker + AI to do the work instead and that could be driven purely to get that silly promotion.

What these companies won't tell you is that they know those on H-1Bs cannot leave unless they find another role - which means one can be threatened over their job to overwork in order to keep it; risking their health as well.

All that BS isn't worth your health.