If you need help resolving a household debate over whether or not to use "the big light," the answer might be to compromise. Turn on the big light in the morning and switch to softer, lamp lighting in the afternoon and evenings.
If you're trying to get some work done or a task that requires mental focus, you might benefit from switching on the overhead light. Bright lighting can increase your alertness and, in some cases, boost your mood. There is even evidence that exposure to electric light can improve cognitive functioning and task completion. This is one reason office environments often use bright overhead lighting.
However, there's a flip side. Exposure to bright light for extended periods can lead to feelings of stress and overstimulation. Think of the exhaustion you feel at 4:00 pm when you're working under the same bright lights that you were at 9:00 that morning.
People who don't like overhead lighting argue that it makes them feel stressed, whereas more ambient lamp lighting is relaxing. Beyond the general feeling that lighting gives off, there's also some research to support this stance. Research generally shows that medium brightness (about 300 to 750 lux) and warmer-colored light are associated with calmness and comfort. Very bright, cool tones are not viewed favorably, even though they can make you feel more alert.
For people with autism or sensory processing disorders, harsh overhead lights can feel extra stressful. People with these conditions are often hypersensitive to sensory stimuli, including bright lights. Dimmer lamp lighting can feel easier on the eyes and mind.
Lighting also influences your sleep-wake cycle, or circadian rhythm. Think of your circadian rhythm as your internal clock, which governs when you feel sleepy versus alert. Before humans used electricity, the human body relied solely on exposure to natural sunlight to regulate the sleep-wake cycle. In modern times, however, humans are exposed to artificial indoor lighting throughout the day, which can disrupt the sleep-wake cycle.
Exposure to light in the evening, in particular, can delay the sleep-wake cycle, or in other words, make you less sleepy and contribute to insomnia. However, most research has focused on the impact of light from electronic devices, like phones, laptops, or e-readers, rather than on bright overhead lighting, so it's hard to say for sure whether overhead lighting affects your sleep more than lamps or candles do. Ultimately, there's no right or wrong, and lighting choices are largely a matter of personal preference.
In the morning, brighter lighting can help you think clearly and increase productivity during both simple and complex tasks. It may also be easier to actually see what you're working on, which is especially important during activities like cooking, when hazards like high heat and sharp knives are involved. Bright lighting can also be helpful in the morning, since it helps suppress melatonin, the sleep hormone, making you feel more alert and ready to take on the day.
As the day goes on, continued exposure to overhead lighting can make you feel stressed, overstimulated, and disrupt your sleep-wake cycle. Afternoon and evening are good times to dim the big light, or swap to lamps and candles for a more relaxed atmosphere. This can help calm your mind and prep you for sleep.