A special hearing was held earlier this year to determine IT company manager Lee Yew Nam's sentence after he was convicted of four charges of physically abusing a subordinate several times in 2013.
The defence asserted that the 45-year-old was suffering from a major depressive disorder at the time, and that it contributed to his offending behaviour.
His lawyers tried to persuade the court to call for a mandatory treatment order (MTO) report before sentencing Lee.
First implemented in 2010, an MTO requires offenders with mental conditions to undergo psychiatric treatment for up to two years in lieu of jail time.
Two expert witnesses - Lee's psychiatrist, Dr Tommy Tan, and the prosecution's Dr Jerome Goh from the Institute of Mental Health - testified .
The prosecution argued that the defence had not satisfied the court that Lee's disorder had contributed to his offending behaviour on all of the charges.
It argued there was also insufficient evidence to show that Lee's irritability and agitation were attributable to the major depressive disorder.
Also, the prosecution argued there was not enough evidence to show he had lost control of himself.