As the seasons change they bring with them hosts of new choices about what to wear.

How to manage to look chic and stay warm? And, as life gets busier, how not to over-heat physically or emotionally.

The selection of something to put on is not just an aesthetic or practical decision. It's also about what suits our mood.

On a minute-by-minute basis, we are assailed by a range of emotions. And every morning we make a decision about what to wear. The two are closely connected. The selection of something to put on is not just an aesthetic or practical decision. It's also about what feels right and what suits our mood. And whether we are conscious of it or not, we all choose clothes that reflect, manage or regulate our emotions. This is what I explore in my latest book Mind What You Wear: The Psychology of Fashion.

Intuitively we all know that certain clothes can transform how we feel. The wrong outfit can make us want to hide, the right one makes us feel like a million dollars. “If I'm well turned out, I walk, talk and act more confidently" said one of my research participants. But can we use this as a force for positive change? I believe we can. And my research is beginning to show how clothing can have real therapeutic properties. A loss of interest in the basics like clothes, personal care and food can herald the onset of a depressive illness.

In the 1980s, Johnson and colleagues spotlighted the relationship between depression and unkempt clothing. Then research by Kwon in 1991 found mood was a significant determiner of clothing choices, especially for women.

This risks creating a pattern of negativity whereby dressing down reinforces negative mood.

I conducted a study in which 9 out of 10 women told me the clothes they wore affected their mood. The women in the study were more likely to wear jeans when they felt low or depressed. More than half of the women also said they would wear a baggy top when depressed, yet hardly any of them said they'd put on a baggy top if they were feeling happy. This risks creating a pattern of negativity whereby dressing down reinforces negative mood.

One research participant, Linda, described this cycle and the coping strategy she uses, “When I feel low or depressed I take less time over my appearance and it gets to a catch 22. To pick myself up sometimes I force myself to get dressed properly and get the makeup on". Psychiatric disorders have been shown to manifest in odd clothing practices. Sufferers of schizophrenia often wear too many or too few clothes, and wearing redundant clothing has been shown to be a readily observable marker for schizophrenia in a psychiatric emergency room. A 1988 American Journal of Psychiatry paper also noted that, before being admitted to a psychiatric hospital, 41% of schizophrenic patients had drastically altered their hairstyle.

More importantly, these changes were made before any other overt sign of psychiatric breakdown manifested. A research team from the Netherlands also discovered that changes in physical appearance accompanied very early indicators of mild psychosis in young adults. This desire to alter one's outer appearance in advance of a psychotic episode shows how clothing is used for mood management. Faced with psychiatric vulnerability associated with the disintegration of the self, appearance manipulations can be an attempt to manage an identity crisis or loss of reality in psychotic disorder.

This link between clothing and emotions - the psychology of fashion - is common to all. People report buying clothes to cheer themselves up ('retail therapy') and many of the women I have surveyed say how they dress can have a massive impact on their confidence. This inevitably plays out in their behaviour, as this respondent described: “If I'm wearing something that makes me less confident, I won't speak up, sometimes I just want to go home!".

For many people a wardrobe crisis can be indicative of a life that's become too humdrum, too narrow and lacking in vitality.

For many people a wardrobe crisis can be indicative of a life that's become too humdrum, too narrow and lacking in vitality. This is particularly true of people who are suffering from stress. My research found a strong relationship between feeling stressed, anxious or depressed and restrictive wardrobe habits. In the study most people said they wore on average between a quarter and half of their wardrobe regularly. However, for in women who were unhappy or stressed, they neglected over 90% of their wardrobe, resorting to wearing less than 10% of it. When a person is stressed their outlook becomes narrower, the range of things they enjoy shrinks and their interests become more limited. It's hardly surprising then to discover that their wardrobe options also narrow down markedly.

My research has shown that helping people to introduce clothing variations and to wear more of their clothes in new creative combinations, can significantly impact upon their sense of wellbeing and reduce episodes of negative mood. This led me to create Wear Something Different, an online programme that sends the person regular prompts to alter, restyle or refresh what they wear. It also profiles their personality and their mood to monitor before and after changes. Who knows, one day we may hear of a doctor or therapist prescribing an outfit rather than a pill to combat feelings of depression.

Click here to buy a book on the Psychology of Fashion Mind What You Wear