Spring at last. Technically, the first day of spring was March 20th. However, any native Montrealer (or Canadian, for that matter) knows we tend to be a little more cautious when it comes to celebrating the end of winter (the snow that fell last weekend is a perfect example of such seemingly rational behaviour).

Nevertheless, with spring arriving and the melting snow coinciding with greater hours of sunlight, I revel in the possibility of spending more time outside that does not involve braving the cold just to switch buildings between classes. Interestingly, people in industrialized nations spend 93 percent of their time indoors, supposedly disconnecting them from the impact of changing weather outside. Despite this fact, I notice one difference that makes this time of year so much better: people are in a better mood.

It’s been known for a long time that cold weather can dampen spirits (e.g. seasonal affective disorder). But I was curious how this information became scientific knowledge; what measurements were used in the process of finding this correlation?

Introduced in 1988, two 10-item mood scales comprised the Positive and Negative Affect Schedule (PANAS), which are brief and easy to administer. This new method was meant to replace earlier measures of self-reported mood that were ineffective, either from low reliability or poor convergent and discriminant validity.

Of the two factors under review, Positive Affect (PA) demonstrates the extent to which a person feels enthusiastic, active, and alert. High PA is associated with extraversion. On the other hand, Negative Affect (NA) is characterized by subjective distress and unpleasant engagement underlying states such as anger, disgust, guilt, fear and nervousness. High NA is associated with anxiety.

Previous scales were used to correlate these two factors with other classes of variables; they found that NA is related to stress and poor coping, whereas PA is related to social activity and satisfaction. The mood questionnaire consists of 60 descriptors (e.g. enthusiastic, interested, afraid, and nervous) arranged in random order, and subjects are asked to rate on a 5-point scale the extent to which they had experienced each mood state.

In 2005, a study looked at the relationship between mood and time spent outside during the months from April to June. Using the PANAS mood scale, their findings showed that mood valence (a single measure obtained by subtracting Negative Activation from Positive Activation) was highly correlated with the weather, determined by the amount of time spent outside. They found that participants spending more than 30 min outside reported higher moods, attributed to the higher temperature and pressure of spring (Fig. 2. a and b).

Why does this all matter? Our mood influences our behaviours, and if weather is an important determinant of our mood, it must also hold a central place in our everyday lives. Admittedly, several other factors may be involved. But just knowing that sunny skies and warmer weather are on their way has put me in a happier mood already.