‘Making them more relaxed’
UK Daily Mail 
Feb 16, 2013
Sleeping pills may be disturbing river ecosystems by turning fish into greedy, risk-taking loners, say researchers.
Scientists studied the behaviour of perch exposed to a sedative which is carried into waterways through sewage.
The drug, a benzodiazepine used to treat anxiety and insomnia called oxazepam, made the fish bolder and less social.
They left the safety of their schools to forage alone – making them vulnerable to predators – and also ate more quickly than normal.
‘Normally perch are shy and hunt in schools,’ said study leader Dr Tomas Brodin, from Umea University in Sweden.