A few sources describing how it is beneficial to bring plants into your living environment...
On Huffington Post: Spring Cleaning: Bring Plants Inside the Home
"Indoor plants can enrich our lives in many ways. One of the benefits is that they can help bring our stress levels down and put us in a better mood."
On Rodale News: Pot a Plant for a Happier Household
"A recent review of the psychological benefits of indoor plants published in the Journal of Environmental Psychology found that our leafy friends can boost mood levels, reduce fatigue, improve reaction time, lower stress, and even boost pain tolerance."
On GreenSpaces blog and via TED: How to Grow Your Own Fresh Air With Plants
Get the details about how this company found that there is a 42% probability of increasing blood oxygen by 1% if one is inside their building for 10 hours, as a result from their use of indoor plants.
On Mother Nature Network: 15 Houseplants for Improving Indoor Air Quality
With input from NASA's study of houseplants as a way to purify the air in space facilities, here are 15 to consider.