'Researchers at Iowa State University found that among college students, as the number of close friends they have approaches the number they think ideal, so feelings of loneliness decrease. It doesn't matter how high or low that number is - that's a subjective judgement - but if a person feels there is a deficit of quality relationships in their lives, then they tend towards loneliness. The Iowa researchers also discovered something which surprised even them. When the number of friends students have exceeds the number they desire, the students begin to feel lonelier again. Perhaps they find having an excess of friends a burden, or perhaps although they consider these friends to be close friends, they aren't close enough.'
Claudia Hammond, The Art of Rest, p.172.