A long-term study conducted by Spanish scientists, spanning over 12 years and involving approximately 460,000 participants, has shown a possible link between continuous exposure to nighttime light and an increased risk of thyroid cancer by up to 55% , particularly among women. The cause is likely the effect of blue light emitted from screens on the secretion of thyroid hormones, although the researchers emphasize that the findings require further investigation.
Dr. Liu Jing , chief physician of the Department of Psychiatry at Anding Hospital in Beijing, points out that reading on a phone screen before bed increases alertness and inhibits the secretion of melatonin, the hormone responsible for regulating sleep. According to studies, using screens for more than two hours can reduce melatonin production by 22% and delay the body's circadian rhythm, leading to difficulty falling asleep and accelerated cellular aging.
The Another study conducted by the Norwegian Institute of Public Health on more than 45,000 people aged 18 to 28 found that every additional hour of phone use before bedtime increases the risk of insomnia by 59% and reduces sleep duration by an average of 24 minutes. Prolonged phone use while lying down also causes eye and neck strain. Looking at the phone at close range weakens the ciliary muscle and causes blurred vision, while poor neck posture contributes to distortion of the natural curve of the cervical spine.
The effect does not stop there, as nighttime use of the phone is also linked to increased appetite and the desire to eat high-calorie foods as a result of increased levels of the hormones adrenaline and dopamine , which causes delayed sleep and negatively affects the quality of deep sleep.
Doctors advise avoiding phone use for at least an hour and a half before bedtime , as this helps the body regulate hormones and naturally boost melatonin production. It's also recommended to reduce screen brightness and adjust ambient lighting to minimize eye strain, while maintaining proper posture so the eyes are at screen level to avoid neck and back pain.