Even candlelight before going to sleep can be bright enough to delay sleep

Even the candlelight before bedtime is bright enough to postpone sleep because the scientist admits that he keeps his lamps & # 39; as dim as possible without bumping into furniture & # 39;

  • People's individual sensitivity to light can be an important health factor
  • Exposure to artificial light after sunset slows an increase in sleep hormone melatonin
  • Some people are so sensitive that only candlelight is enough to keep them awake
  • While others do not experience the same effect until they see sunrise brightness

Only the glow of a few candles could be enough to keep people awake at night, according to research.

Bright light can slow the production of melatonin in the body, a hormone that peaks in the evening and makes us sleepy.

And while sleep experts often seek advice against the use of telephones, computers or TV before bedtime, even lower light levels may be sufficient to disrupt sleep.

Researchers studying how different light levels affected people found the tolerance of some people up to 58 times higher than that of others.


A scientist who was involved in the research even admitted that he kept his house & # 39; as weak as I can without holding back his furniture & # 39; stores.

Researchers in Australia tested the effects of artificial light on people's sleep patterns and discovered that some people could withstand 60 times as much light as others before it affected their ability to snooze (stock image)

Researchers in Australia tested the effects of artificial light on people's sleep patterns and discovered that some people could withstand 60 times as much light as others before it affected their ability to snooze (stock image)

Scientists from Monash University tested the effects of artificial light on a group of 55 men and women in the evening.

They found a light level that was too low to read – measured as 24.6 lux (lux equals one lumen per square meter) – was enough to stunt melatonin 50% in the average person.

However, some people experienced the same decrease in light levels of just a quarter as strong (six lux), which were equal to a few candles or half as bright as a street lamp.


Melatonin is a hormone that determines how people feel asleep or awake.


The hormone is produced in the pineal gland in the brain and its release in the body is controlled by light.

During the day, when the eye absorbs light, the melatonin levels in the body are low and we feel awake as a result.

But when darkness collapses and the amount of light absorbed by the eye decreases (although this is disturbed by artificial light in modern societies), more melatonin circulates around the body.

Melatonin prepares the body for sleep by lowering the heart rate, lowering blood pressure and changing the way heat is stored in the body – the body's core temperature drops while the outside of the body and limbs become warmer.

The hormone also makes people sleepy.


Melatonin supplements can be used to help sleep in people with problems, as well as for certain medical conditions such as tinnitus or Alzheimer's disease.

sources: Medical news today and Journal of Applied Physics

At the same time, those with a higher tolerance did not have the 50 percent decrease in their melatonin levels, unless exposed to 350 lux, about the brightness of a sunrise.

& # 39; For some people, a weak reading light can be just as good as daylight, and for others it is just as much darkness & # 39 ;, said associate professor Sean Cain. New scientist.

While people can't test their own light sensitivity, Professor Cain said it's best to be careful.


He added: & # 39; I keep my lights as dark as I can without bumping into furniture. & # 39;

The intensity of a light seemed to have a direct effect on how long it delayed an increase in melatonin, which would affect how long sleep lasted.

A brightness of 10 lux, roughly the same as a street lamp, can delay sleep by 22 minutes, the study found.

While 30 lux, the lowest recommended reading light, led to a 77 minute delay, and 50 lux, equivalent to about a 45-watt incandescent lamp, added 109 minutes.

Professor Cain and his colleagues said sensitive people to light may be an undervalued measure of how the body clock affects overall health.


In the study, the group of 55 people followed a strict sleep pattern for up to eight weeks and were exposed to light and measured for one night a week in a laboratory.

The research was published in the journal PNAS.

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