Shorter days and lack of sunlight can greatly affect one’s mental state. People often suffer from seasonal affective disorder (SAD) during the fall and winter months due to ...

A review of 17 studies has cast doubt on the widely held belief that depression is caused by low levels of serotonin in the brain. Ask anyone what causes depression and chances are they’ll ...

Finally, to examine how the neurotransmitter influenced immune tolerance to antigens, the researchers gave serotonin to germ-free neonates, which lack gut microbes, and exposed the animals to dietary ...

Sunlight and vitamin D deficiency: Lack of sunlight may lower serotonin levels, while a lack of vitamin D—essential for serotonin activity—can invoke symptoms of SAD. Light therapy ...

Stop and think: A drop in serotonin can lead to increased stress. SAD also manifests in a lack of focus, feeling down, loss of interest in activities, tiredness, and getting easily annoyed.