Sleep needs two signals, and we cancel both: a sleep expert says screens before bed are a "direct attack" on melatonin

When we talk about bad sleep, we usually blame the mattress, the pillow or the afternoon coffee. Light rarely makes the list. Yet according to Dr Sofía Rodríguez Moroder, a specialist in dental sleep medicine at the Craneo Salud clinic, it is one of the most underestimated factors.

"The onset of sleep is a very delicate biological process," she explains. To fall asleep, the body needs two signals: a gradual drop in body temperature and a gradual dimming of light. The problem is that modern life has replaced both with artificial stimuli.

Melatonin doesn't read messages

Light is one of the main cues the brain uses to set the circadian rhythm, the internal clock that decides when we are awake and when we should sleep. When natural light fades at dusk, the pineal gland starts releasing melatonin, the hormone that helps sleep begin and last. The intense blue light from screens slows that release. The message to the brain is clear: it's daytime, stay awake.

That is why the expert does not mince words: sitting at home in front of the TV or a phone before bed is a "direct attack" on that process.

89,000 people and one uncomfortable number

A study published in the scientific journal Proceedings of the National Academy of Sciences, which analysed the light exposure habits of almost 89,000 adults, found that those exposed to the most light at night had a 21 to 34 percent higher risk of death from any cause compared with those who slept in darker rooms. An important caveat: the data alone do not prove that light directly causes the higher risk. They show that night-time lighting deserves far more research than it gets.

What actually helps

The prescription is not expensive. Screens go off one to two hours before bed, and the phone goes into flight mode. Bright white lights in the evening are swapped for dim lamps. The TV does not stay on in the background "for company", and notifications are not checked in bed. The nicest tip is also the cheapest: watch the sunset from a balcony, a terrace or your doorstep, as a sign that the day is ending.

Our grandmothers had no sleep-tracking apps, but they had dark rooms and evenings without screens. How many of us fall asleep today with a phone in hand, then wonder why the alarm clock sounds like a punishment?