Tuesday, October 3, 2023

Dark side of bright lights

Executive Summary

The normal 24–hour day–night cycle is synchronised with our body’s circadian rhythm, which regulates levels of many hormones in the body. However, nighttime lights, especially the new blue LEDs, throw this cycle out of whack.

Artificial lights tell your pineal gland to stop producing melatonin. Such disturbance in melatonin secretion has been found to be linked to cancer, diabetes, heart disease, and obesity.

The article explains these points and suggests some preventive strategies.

For millennia, our life was centred around the daylight. Our main source of light was the sun. There was very little artificial lighting, except a few oil lamps, which did not give bright light.

These days, we have many light sources. From incandescent (light bulbs) and fluorescent (tube lights) to modern LED lights, our world is now flooded with bright lights.

Research is ongoing about how to get even more light with lesser energy. Some moonshot projects are even considering launching artificial moons into the sky. This, they feel, will give far more light outdoors in the evening, than just the moonlight. So, you can expect more lighting at night as the years go by.

Problem with artificial lights

Circadian rhythm

Over millions of years, the steady 24–hour cycle of daylight followed by dark nights adjusted our body’s biorhythm to almost 24 hours. This is called the Circadian rhythm.

Many of the body processes are synchronised to this 24–hour cycle. It regulates levels of many hormones in the body.

Now, the bright artificial lights confuse many insects, birds, and other animals. They are known to be affected by these artificial lights.

But, we don’t expect to be affected by them, because we ‘know’ the lights are artificial. Well, not true. Our sensory organs still follow their biological ways, not our logical ways.

Pineal gland and melatonin

For example, there is a pea–shaped gland called Pineal gland in our brain. Its purpose is not well known. However, we know that it secretes a hormone called Melatonin.

The darkness stimulates the production of melatonin in the pineal gland. Melatonin makes you drowsy. It helps you sleep better, though we don’t exactly know how melatonin works.

When the first rays of sunlight fall on your retina, they stimulate a part of your brain. That, in turn, tells the pineal gland to stop the production of melatonin. This is a signal for your circadian rhythm, or the body clock, that a day has begun.

With the sunset, this process is reversed and the pineal gland gets back to producing melatonin. The cycle starts all over again.

If you face bright lights, the pineal gland does not start producing melatonin. So, it could be late in the night, but your body still thinks it is daylight. This throws your circadian rhythm into disarray.

One day of such disruption and you have a disturbed body and mind. But if this continues for months and years, there are serious medical problems.

Medical problems

Lower Melatonin production, due to artificial lights, may explain the association with cancer.

When our biological clock goes for a toss, it possibly causes higher blood sugar. This can lead to pre-diabetes.

The same problem also lower levels of leptin, a hormone that makes you feel full. This can lead to overeating and obesity.

Thus, the artificial light that we use at night, especially from our TV, mobile phones and computer screens, may contribute to obesity, cancer, diabetes, and heart disease. Read: Blue light has a dark side.

Even dim lights, such as table lamps, can interfere with circadian rhythm and melatonin secretion. This can cause shortened sleep. A shortfall in sleep is linked to depression, diabetes, and heart disease. Read on this website: Are you suffering from excessive daytime sleepiness?

Blue lights

The bigger culprit among all the colours of light is the blue one. The bluish lights increase attention, reaction time, and mood — a boon in the daytime but a bane for sleeping at night.

The light from older bulbs was more orange and less blue. The newer LED lamps and screens are predominantly bluish. Blue LEDs shift circadian rhythms by 3 hours, which is twice as much as that by other colours, such as green LED lamps.

The blue lights can also damage your eyesight permanently. Read on this website: How blue rays damage your eyesight and what to do for that. Of course, this is a different problem from the one discussed above, which is about the damage due to incomplete sleep.

In conclusion

Avoid looking at bright screens at least 2 hours before bedtime.

Switch to incandescent lighting (light bulbs) at least 2 hours before bedtime, if that is possible in your country (some countries don’t have incandescent bulbs because they are not energy–efficient).

Get exposure to a lot of daylight during the day which will boost the ability to sleep well at night.

First Published on: 31st December 2017
Image credit: fanjianhua on Freepik
Last Updated on: 1st July 2023


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