Why you shouldn't fall asleep in front of the TV

Veröffentlicht am: August 01, 2024
Irina Fink
Irina Fink

Naturopath

In a recent study published in the journal JAMA Internal Medicine, it was not the duration and quality of sleep that appeared to influence weight gain and the incidence of obesity, but rather artificial light at night that was the problem.

This does not even have to be a significant exposure to light. In the study, weight gain was greatest when the test subjects slept with the light on in the room or with the TV on.

Artificial light at night increases the risk of obesity

One study involved 43,722 women between the ages of 35 and 74. At the start of the study, none of the participants were shift workers, daytime sleepers or pregnant.

The study results show: Compared to women who are not exposed to artificial lighting at night, sleeping with the TV on or lights in the room is associated with a greater risk of gaining about 5 kg or more. The body mass index can increase by 10 percent or more. This habit can lead to overweight or obesity over time.

The scientists explain: "Nocturnal exposure to artificial light during sleep appears to be associated with higher weight. This finding suggests that artificial light at night should be included in the discussion on obesity prevention.

As mentioned above, the amount of weight gain depends on the type of light exposure. Sleeping with a small night light is not associated with weight gain, but sleeping in a room with outside light can lead to moderate weight gain. Women who sleep with a light or TV on were 17 percent more likely to gain about 5 kg or more.

Chandra Jackson, Ph.D., director of the National Institute of Environmental Health Sciences Social and Environmental Determinants of Health Equity Group and co-author of the study, explained that the study could have implications for people in urban areas, where artificial light sources such as streetlights and neon signs can lead to impairments in the sleep hormone melatonin.

She continues: "Humans are genetically adapted to a natural environment consisting of sunlight during the day and darkness at night. Artificial light at night can alter hormones and other biological processes in a way that increases the risk of health problems such as obesity."

➤Order Melatonin now!

Why exposure to light at night is dangerous

Even low levels of artificial light at night lead to disruptions in the natural light and dark cycle, which can have far-reaching effects on health. In a study by researchers at Ohio State University, light exposure at night was even linked to immune and hormonal dysfunction.

For their study, the scientists used hamsters that normally sleep during the day. For nine weeks, one group was exposed to dim light at night, while a control group was exposed to typical light during the day and darkness at night. Dim light at night not only led to increased body mass in the hamsters, but also affected the animals' offspring.

Although the offspring were reared under normal light conditions, with light during the day and darkness at night, the parental history (artificial light at night) led to a reduced immune response and reduced endocrine activity in the young animals.

These impairments were passed on by the genetic material of one of the parents. It did not matter whether the mother or the father was exposed to weak light at night; the effect could be traced back to both parents.

The impaired adaptive immune function seen in the hamster offspring illustrates a transgenerational effect of light at night: although the DNA sequence was not altered, the light affected the epigenetic expression of the DNA.

"Taken together, these data suggest that exposure to dLAN [dim light at night] has transgenerational effects on endocrine-immune function that may be mediated by global changes in the epigenetic landscape of the immune system," the researchers explain.

➤Buy Ashwagandha powder now!

Light at night changes the sleep hormone melatonin

Melatonin is an important hormone produced by the body's pineal gland. One of its main functions is to regulate your body's biorhythm. When it gets dark, your brain starts to release melatonin (usually around 21:00 or 22:00), which makes you sleepy.

The levels normally remain elevated for around 12 hours. As soon as the sun rises, the pineal gland reduces production and the levels in the blood fall until melatonin can barely be detected.

If your biorhythm is disturbed, for example due to shift work, jet lag or exposure to light at night, your body produces less melatonin.

"Indoor light profoundly suppresses melatonin levels and shortens the body's own nighttime duration," write researchers in the Journal of Clinical Endocrinology & Metabolism. "Thus, regular electric lighting in the late evening interferes with melatonin signaling and could therefore affect your sleep, thermoregulation, blood pressure, and glucose homeostasis."

As well as helping you sleep, research suggests that melatonin can prevent cancer. It acts as a comprehensive anti-cancer agent to prevent the development, progression and metastasis of cancer. In a clinical trial, patients with glioblastoma received either radiation therapy and melatonin or radiation alone. Six of the 14 patients who received melatonin were still alive one year later. Among the subjects who only received radiation, only one of the 16 study participants in this group survived.

Another study found that melatonin reduces the growth of prostate cancer. There is also a strong link between melatonin and breast cancer. For example, women who live in areas with a lot of night-time lighting have a higher risk of breast cancer than those who live in areas where it is dark at night.

In fact, in countries with the highest levels of light at night, the risk of breast cancer is 30 to 50 percent higher than in countries with the lowest levels of light at night.

Light at night can even affect brain health

Another reason to lower the light level in your bedroom is to protect your brain health and even your mood. Twenty men slept in a laboratory under different lighting conditions: two nights with no light exposure and a third night in low light of five or ten lux (for comparison: twilight = 10.8 lux).

After the second and third night, participants performed working memory tests during functional magnetic resonance imaging (fMRI). The aim was to investigate the effects of this low-level light exposure during sleep on functional brain activation during a working memory task the next day.

Sleeping in light (10 lux) led to reduced activation in the right inferior frontal gyrus, an area of the brain involved in response inhibition, attentional control and recognition of relevant cues during task performance.

Sleeping in very low light (5 lux) had no statistically significant effect on the participants' brain activity. This indicates that our brains can tolerate very low light levels, but that even 10 lux can impair cognition and working memory.

However, in a study with hamsters, four weeks of exposure to very weak light (5 lux) at night led to symptoms of depression. These only disappeared two weeks after the weak light source was switched off at night.

➤Buy GABA capsules now!

Switch off screens at night

It's not just the light from televisions that is problematic. Screens, tablets and cell phones with LED backlighting also significantly suppress melatonin production at night and affect your feeling of tiredness. If your brain is exposed to blue light at night, it receives a message that is not in sync with your biorhythm. This can lead to serious health problems.

In 2011, for example, researchers confirmed in a study that the evening use of computers with LED backlighting disrupts the biorhythm. In 13 young men, looking at an LED-lit screen for five hours at night led to a significant suppression of melatonin production and thus fatigue.

However, the effects are even more extensive. LEDs lack infrared light, which is favorable for us, and have an excess of blue light. This generates reactive oxygen species (ROS) that impair your vision and may lead to age-related macular degeneration (AMD). Macular degeneration is one of the main causes of blindness in older people.

LED lights can also exacerbate mitochondrial dysfunction, leading to chronic diseases ranging from metabolic disorders to cancer. Therefore, if you (have to) look at screens at night, you should definitely block blue light. In the case of your computer, there are programs available that automatically lower the color temperature of your screen at night.

➤Order Melatonin Spray now!

For optimum health, you need bright light during the day and darkness at night

Sleeping in a completely darkened room - without illumination from an alarm clock, television, cell phone or other sources ...

  • improves your sleep quality
  • helps you to maintain a healthy weight
  • contributes to your general health

When you get up at night to use the bathroom, you should not switch on any lights so that your melatonin production is not interrupted.

Remove all light-producing alarm clocks from the bedroom and use blackout curtains to stop light entering the room through your windows. Alternatively, you can wear an eye mask to block out light pollution. Even before you go to bed, you can wear blue light-blocking glasses after sunset, for example, to prevent blue light exposure.

Just as important as sleeping in dark rooms is getting enough sunshine in the morning. Your melatonin production is influenced by the amount of light or darkness. When it is bright, your body naturally produces less melatonin. At least 15 minutes of sunlight in the morning helps to regulate the production of melatonin and reduce the level to normal daytime values so that you feel awake during the day and sleep better at night.

The good news is that even if you have slept with the TV on once, this is a simple and straightforward way to significantly improve your health. If you often fall asleep with the TV on, banish it from your bedroom and go to bed as soon as you feel tired.

Summary

  • Women have an increased risk of weight gain if they are exposed to external light sources at night. Compared to women who are not exposed to artificial lighting at night, the risk of gaining about 5 kg or more increases. The body mass index can even increase by 10 percent or more.
  • Sleeping with a small night light is not associated with weight gain, but sleeping in a room with outside light can lead to moderate weight gain.
  • Women who sleep with the lights on or the TV on are 17% more likely to have gained around 5 kg or more in a follow-up study.
  • Artificial light at night can affect the sleep hormone melatonin and lead to a variety of health problems beyond weight gain.
  • So if you often sleep with the TV on, this can be detrimental to your efforts to maintain a healthy weight. There is a strong link between sleep and obesity: those who regularly sleep only a few hours have an increased risk of obesity.

 

Sources (in English):

Park, Y. M., White, A. J., Jackson, C. L. (2019, June). Association of Exposure to Artificial Light at Night While Sleeping With Risk of Obesity in Women. JAMA Internal Medicine, doi: 10.1001/jamainternmed.2019.0571

Potter, G. D., Cade, J. E. & Hardie, L. J. (2017, July). Longer sleep is associated with lower BMI and favorable metabolic profiles in UK adults: Findings from the National Diet and Nutrition Survey. PLOS ONE, doi: 10.1371/journal.pone.0182195

Arnette, R. (2019, June). Sleeping with artificial light at night associated with weight gain in women. Eliminating light while sleeping could reduce obesity. National Institutes of Health, Verfügbar unter: [https://www.nih.gov/news-events/news-releases/sleeping-artificial-light-night-associated-weight-gain-women]

Googley, J. J., Chamberlain, K., Smith, K. A., Khalsa, S. B., Rajaratnam, S. M., Van Reen, E. et al. (2011, March). Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans. The Journal of Clinical Endocrinology and Metabolism, Volume 96, Issue 3, doi: 10.1210/jc.2010-2098

Cisse, Y. M., Russart, K. L. & Nelson, R. J. (2017, March). Parental Exposure to Dim Light at Night Prior to Mating Alters Offspring Adaptive Immunity. Scientific Reports, 45497, doi: 10.1038/srep45497

Reiter, R. J., Rosales-Corral, S. A., Tan, D. X., Acuna-Castroviejo, D., Quin, L., Yang, S. F. et al. (2017, April). Melatonin, a Full Service Anti-Cancer Agent: Inhibition of Initiation, Progression and Metastasis. International Journal of Molecular Sciences, 18(4): 843, doi: 10.3390/ijms18040843

Lissoni, P., Meregalli, S., Nosetto, L., Barni, S., Tancini, G., Fossati, V. et al. (1996, January-February). Increased survival time in brain glioblastomas by a radioneuroendocrine strategy with radiotherapy plus melatonin compared to radiotherapy alone. Oncology, 53(1):43-6, doi: 10.1159/000227533

Sainz, R. M., Mayo, J. C., Tan, D. X., Leon, J., Manchester, L. & Reiter, R. J. (2005, April). Melatonin reduces prostate cancer cell growth leading to neuroendocrine differentiation via a receptor and PKA independent mechanism. The Prostate, 63(1):29-43, doi: 10.1002/pros.20155

Kloog, I., Stevens, R. G., Haim, A. & Portnov, B. A. (2010, December). Nighttime light level co-distributes with breast cancer incidence worldwide. Cancer Causes & Control, 21(12):2059-68, doi: 10.1007/s10552-010-9624-4

Kang, S. G., Yoon, H. K., Cho, C. H., Kwon, S., Kang, J., Park, Y. M. et al. (2016, November). Decrease in fMRI brain activation during working memory performed after sleeping under 10 lux light. Scientific Reports, 36731, doi: 10.1038/srep36731

Bedrosian, T. A., Weil, Z. M. & Nelson, R. J. (2012, July). Chronic dim light at night provokes reversible depression-like phenotype: possible role for TNF. Molecular Psychiatry, 930–936, doi: 10.1038/mp.2012.96

Cajochen, C., Frey, S., Anders, D., Späti, J., Bues, M., Pross, A., Mager, R. et al. (2011, May). Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance. Journal of Applied Physiology, 110(5):1432-8, doi: 10.1152/japplphysiol.00165.2011