Melburnians awoke this morning to temperatures hovering around five degrees, but it felt even colder thanks to chilly north-easterly winds. Out in the suburbs it was even crisper.

The weather bureau is forecasting a top of 17 degrees in the city today, and temperatures are not expected to reach above the mid-teens for the rest of the week.

Conditions will be slightly different on the weekend – it won't be any warmer, but there's the added bonus of a greater chance of rainfall.

But it is not as though the colder weather has come out of nowhere. Tuesday was a freezing 17 degrees, and Melburnians shivered through the coldest morning since August of last year.

As the days keep getting shorter and temperatures keep dropping, it is enough to make anyone feel glum, but to say the seasonal changes cause depression is an overstatement.

Swinburne University Psychological Sciences Professor Greg Murray doubts whether seasonal affective disorder actually exists.

Professor Murray says people suffering from seasonal affective disorder ("winter blues") respond to anti-depressants and bright lights, but no more than someone afflicted with depression would.

A common claim is that people in the north of Norway, where it is dark for several months of the year, suffer higher rates of depression during winter because of the constant gloom.

But when researchers looked at the data, they found they were no more likely to report feeling depressed than other Norwegians.

He said the greater incidence of depression in winter months could be more tied to lifestyle factors. When it starts getting colder, we can end up socialising less, exercising less and sleeping in more – which can all lead to poorer mental health.

So even though the weather is miserable, don't let it get you down.