According to this article, significant sleep loss can mean irreversible damage to brain cells. This article said sleep loss for a few hours- like staying up late to study for an exam is not an issue. The concern is for shift workers such as nurses or law-enforcement, or perhaps people with insomnia. Missing large chunks of sleep over time can literally kill brain cells. So, what can you do? Request a work schedule that gives you the maximum amount of sleep possible and if you struggle with insomnia, talk to your doctor.