Great writers are said to be night owls as they find the night more productive than the day even though there are debates over body rhythms and the writing process. “I often think that the night is more alive and more richly coloured than the day,” says Vincent Van Gogh, a Dutch post-impressionist painter, while Mahatma Gandhi, a great Indian political philosopher, says, “In the midst of darkness, light persists.” But today it is nearly impossible to find natural darkness even at night. This is not good, not good at all, said experts. They stressed the need for raising awareness against the nighttime excessive artificial lighting in Dhaka, considering its dire impacts on the biological clock of the human bodies and lives of other animals including birds, bugs and insects that navigate based on light. Read:Experts lament lack of steps to check air pollution in Dhaka city Though light pollution is a new phenomenon in the country, some major cities in the world have started acting against the nighttime excessive lighting as it badly affects the mental and physical health of the humans and the lives of other animals, they said. Alongside controlling air, noise and other environmental pollution, the authorities concerned should now think about the nighttime light pollution also to protect public health and ecosystem as well as save electricity by limiting excessive outdoor lighting, the experts said. Most recently, a video has gone viral on the social media that some sparrows took shelter inside a house in Dhaka, being frightened by excessive lightings and sounds generated by fireworks and Fanus (sky lantern) during the 31st night celebrations. Public health expert Dr MH Chowdhury Lelin said every animal leads its life through a circadian clock, but the light pollution changes the biological clock keeping serious impacts on mental and physical health. “The excessive lighting causes an overstimulated nervous system, headache, sleeplessness, high blood pressure, high heartbeat, irritable mood and vision power of a man. So, it ultimately hampers the normal activities of a human body and one’s mental health,” he said. Dr Lelin, also an environmental activist, said the nighttime excessive lighting hampers the sleeping pattern of the human and most birds and other wildlife which badly affect their normal lives during the day. Besides, he said, the nighttime artificial lighting severely affected the nocturnal animals that they can’t intake foods due to the light pollution. Even the nighttime lighting has an adverse impact on plants. So, the light pollution affects the whole ecosystem. The excessive indoor lighting despite having enough light during the daytime is also considered light pollution, said Dr Lelin. Biomedical scientist and educationist Prof Dr Liaquat Ali said the light pollution can elicit melatonin suppression, though the hormone acts as an antioxidant. “If the melatonin secretion declines, it damages its antioxidant effect, disturbs biological clock and immunity. So, the light pollution may cause different diseases like obesity, diabetes and cancer,” he said. It also has adverse impacts on mental health, creating depression and disturbing sleep pattern, said Dr Liaquat Ali.

A study of the University of Michigan (UM) suggested that human-caused noise and light pollution can harm individual species of bird populations.