Seoul, May 5 (IANS): Nearly 1 in 5 children in South Korea said they are unhappy, citing pressure to do well at school as the biggest reason, a survey revealed on Thursday.

According to the poll conducted by the health ministry and the National Centre for the Rights of the Child, 81.4 per cent of those surveyed said they are either "somewhat happy" or "very happy", while 18.6 per cent said they are "not very happy" or "not at all happy", reports Yonhap News Agency.

Of the children who said they are unhappy, 33.9 per cent chose pressure to do well at school as the top reason, followed by uncertainty about the future at 27.5 per cent.

Other reasons included economic difficulties, a troubled family, difficult relationships with friends and unhappiness about their physical appearance.

The latest edition of the annual survey was conducted online from July 16 to October 29 last year on 1,270 children and teenagers in classes from 4-12.