Shawn Achor looked at the argument for taking more vacation:

• Americans are taking less vacation than ever before.
• This is a pity since research indicates that those who take all of their vacation are 7% more likely to get promoted than those who chose not to take 11 or more days of it.
• The type of vacation matters. Those that are badly planned and stressful don’t refresh employees as much.
• The ideal vacation is planned a month in advance, discussed with co-workers, and takes place far away from your home city.
• Your managers will thank you for it – most associate personal happiness with productivity, and 31% want employees to take vacation to be more happy.

You can read more about the research and what it shows here.

Source: Harvard Business Review