When we talk about well-being, we often think of something abstract, such as feeling calm, sleeping well, having energy, connecting with others, or living with less stress. But well-being also has a deeply biological dimension. It does not happen only “in the mind.” It happens in the body, the brain, the hormones, the metabolism, and even in the environments we inhabit.
Every day, our bodies translate what we experience into biological signals. A night of poor sleep, the constant noise of the city, pollution, an unhealthy diet, or prolonged periods of stress can alter our hormones and neurotransmitters. In the same way, walking, disconnecting, resting, eating better, dancing, talking with someone we love, or spending time in green spaces also leave a mark on our biology. Systems biology helps us understand that these actions do not work in isolation, but rather as part of a network in which hormones, metabolism, the brain, inflammation, and the environment constantly interact.
Molecules such as cortisol, oxytocin, serotonin, dopamine, and endorphins are involved in processes related to stress, social bonding, motivation, pleasure, pain, and repair. They are not “magic happiness molecules,” but part of a complex and coordinated network that helps the body adapt to what happens both inside and outside of us.
An interesting question we explore at the Hospital del Mar Research Institute is how we can measure these signals. Traditionally, they have been studied in blood, saliva, and urine, but these samples often reflect only very specific moments of the day rather than long-term biological processes. We have discovered that tissues such as fingernails can act as small biological archives. As they grow, they can bioaccumulate certain molecules and provide a more integrated picture of stress or wellbeing over weeks or months. This opens a promising path for studying how stress, lifestyle habits, and the urban environment are linked to wellbeing in a more stable and long-term way.
Understanding the biochemistry of wellbeing does not mean reducing life to molecules. It means recognizing that mental and physical health depend not only on individual choices, but also on the conditions in which we live. Everything ends up being connected. The city, work, sleep, nutrition, relationships, and access to healthy green spaces.
Perhaps wellbeing is not a perfect state we must achieve, but rather an ongoing conversation between our body, our understanding of life itself, and the world around us. And the better we understand that conversation, the better we can take care of ourselves and the communities in which we live.
Biomedical researcher and biostatistician at the Hospital del Mar Research Institute in Barcelona. His work combines metabolomics, epidemiology, data science, and systems biology to study how metabolism, the environment, and lifestyle habits are connected to health and biomedicine. He is also actively involved in science communication projects focused on wellbeing, neurobiology, and urban health.