What makes you happy? Score the following activities out of 10: laughing with friends; playing games and sports; time in bed; time in nature; time spent online.

Scientists are trying to understand what creates the perfect day. One group of researchers have tracked the time people spend on each activity, working out what combination causes most happiness. 

Some of the results were obvious: socialising for more than 30 minutes lifted everyone's spirits, while spending time with friends had "an almost boundlessly positive effect". Other results were more surprising: six hours of work had no impact on happiness, while a 15-minute commute actually improved people's moods.¹

Another group of researchers are relying on an app that messages participants several times a day to ask for a rating of how they are feeling, from "very bad" to "very good". The app promises to help users understand what makes them happy, as well as helping spot mental health problems early. According to one journalist, mood tracker apps "put a psychiatrist in your pocket".²

However, critics warn that measuring mood this way mistakes happiness for something more fleeting. For instance, Professor Martin Seligman, who helped found the field of happiness research, thinks focusing on "moment-to-moment mood [is] a recipe for depression and anxiety".³

According to some researchers, "there is surprisingly little support" for many recommended happiness strategies, such as meditation, exercise and time spent in nature.⁴ Others argue that it is meaningless to ascribe numerical values to experiences as different as laughing, eating ice cream, or fussing over a pet.

Besides, scientists already have a clear idea of what makes people happy. At least, that is the conclusion of Robert Waldinger, director of the Harvard Study of Adult Development, the longest scientific study on happiness ever conducted.

Waldinger divides happiness into two categories: hedonic, which means in-the-moment pleasure; and eudaimonic, which means having a sense of purpose or fulfilment. His research shows that eudaimonic happiness is more important for long-term wellbeing.

The study has also shown the importance of relationships. People who "kept prioritising connections... were the people who stay happier and healthier".⁵ Relationships not only boost our mood, but also help us to live longer. Some research even suggests that social isolation is as bad for a person's health as smoking cigarettes or never exercising.⁶

Does this mean that happiness tracking is a waste of time? Not if it helps people to live in a more reflective way or understand their own emotional patterns. But it will not catch the sense of a worthwhile life that comes from eudaimonic pleasure and lasting relationships.

Just ask Kevin Sandler, who has tracked his mood every 15 minutes since 2018. Eventually he realised that: "Happiness is not the end-all goal I was looking for."⁷

But can we really measure happiness?

Yes: Modern technology allows scientists to track people's levels of contentment at every moment. Happiness can be measured like fitness and other health markers.

No: Studies that focus on moment-to-moment happiness miss deeper sources of contentment. Focusing on relationships, rather than our mood, makes life worthwhile.

Or... Momentary pleasures and a more lasting sense of purpose are both required for a happy life. But everybody has to find the right balance for themselves.