Bad news for Burundi which has come last in the UN's annual World Happiness Report.
The index ranked 156 countries based on factors including life expectancy, social freedom and absence of corruption.
Top of the chart was Finland, which rose from fifth place to push out Norway.
In 2016, Burundi came bottom of the list, but rose to 154th place in 2017, when the Central African Republic was found to be the least happiest country.
Burundi plunged into crisis when President Pierre Nkurunziza's bid for re-election to a third term in 2015 sparked protests by opposition supporters who said the move was unconstitutional.