Bright light, such as sunlight on a clear midsummer day, makes us feel positive, alert and energised naturally. However, many people don't get enough bright light during their day, particularly in autumn and winter. The short, dark days can trigger symptoms of 'winter blues', like lack of energy, wanting to sleep more and socialise less.
Vitamin L is a
registered trademark of Outside In (Cambridge) Ltd. It is not a vitamin, but a
reference to mood-enhancing properties of light.