How Does Light Affect Our Mood? The Secret Regulator of Our Well-Being

The Dance of the Body Clock and Hormones

Light doesn’t simply “cheer us up”—it triggers an extremely precise hormonal process in our bodies through our eyes. Once you understand how this system works, you can take control of the winter blues.

The story has two main characters: melatonin and serotonin.

1. Melatonin: The hormone responsible for sleep

Melatonin’s job is to prepare your body for rest. Normally, its levels begin to rise in the evening as it gets dark.

In winter, however, on overcast, dark mornings, our bodies don’t receive a strong enough light signal to “switch off” this hormone. That’s why you still feel groggy and sleepy at 9 a.m.: biologically, your body is still stuck in nighttime mode.

2. Serotonin: The hormone responsible for activity and good spirits

Serotonin is often referred to as the happiness hormone. Research has shown that a lack of light directly reduces serotonin activity in the brain.

In autumn and winter, less natural light causes our serotonin levels to drop, which can lead to fatigue, difficulty concentrating, carbohydrate cravings, and persistent low mood.

The solution: Reset your body’s clock!

The key to the solution is proper timing. Bright, intense light in the morning tells your brain that the day has begun: it immediately stops melatonin production and activates energizing processes.

If natural sunlight is lacking, using a 10,000-lux light therapy lamp for 20–30 minutes a day (for example, while having your morning coffee or reading) can provide your body with exactly this clear morning light signal. Being UV-free is the most fundamental safety requirement, so your eyes remain completely safe over the long term.

You’re not only waking up your eyes—you’re also guiding your hormonal balance back into its proper, natural rhythm.