According to Harvard Medical School, the gains made from time spent getting extra work done will ultimately be lost (and then some) by the moodiness and lack of focus you bring to work the next day. Travis Bradberry elaborates in an article for SBS.
The University of Rochester has found that sleeping removes toxins in neurons that build up while awake—something that caffeine cannot do. Sleep deprivation has been linked to heart attacks, strokes, type 2 diabetes, and obesity. It also weakens your immune system, wrecks your skin, and reduces sperm count. You really need to target seven to nine hours of sleep a night to keep your head in the game. Bradberry goes on to list some tips for better sleep. These include avoiding sleeping pills, skipping caffeine after lunch, avoiding blue light at night, maintaining a consistent sleep schedule, and meditating. To read about these ideas in their full depth, you can view Bradberry’s article here: http://www.sbs.com.au/news/article/2014/12/09/sleep-deprivation-killing-your-career