The tilt of the Earth's axis as it orbits around the sun causes seasons. Different parts of the world receive different amounts of sunlight depending on that angle. In the Northern Hemisphere, we experience winter from December to March, while the Southern Hemisphere soaks up the sun.
It's normal to feel sluggish during the winter. Cold temperatures and fewer hours of sunlight can mean less time outdoors and more time staring at our screens. For some people, these cold-weather habits may contribute to a sleep disruption, known as winter insomnia. This isn't a clinical condition, but it might begin or worsen during the winter months.
When should I use my bright light therapy lamp? You should use it every morning (as soon as possible after waking up) during the months when you experience SAD symptoms. It is not advised to use a bright light therapy lamp in the afternoon or evening, as it can mess with your circadian rhythm/sleep cycle. You should try to use it for 20-30 minutes each day.