National Center for Complementary and Integrative Health (NCCIH) Lecture: “Lighting Up Our Lives: How Light Influences Our Mental and Physical Health”

Lecture Type: Online Video

Time: 69 minutes 17 seconds

Date: June 30, 2020

Speakers: Dr. Helen Burgess, Ph.D.

Topic: Impacts of Light on Mental and Physical Health

 You can access the lecture by clicking the link here.

https://videocast.nih.gov/watch=37830

Circadian Rhythms and Sleep

Dr. Helen Burgess is a professor in the department of psychiatry, as well as a researcher in the sleep and circadian research laboratory, at the University of Michigan. She studies the impact of light on human health.

Dr. Burgess and colleagues study circadian rhythms. A circadian rhythm is your body’s internal clock signaling whether it is day or night. This clock releases different cocktails of hormones throughout the day to prepare you either for sleep or activity.

There are special photoreceptors in the eye – called intrinsically photosensitive retinal ganglion cells (ipRGCs) –  that are linked to a center of the brain called the suprachiasmatic nucleus (SCN). In response to light, the brain interprets that it is daytime. On the other hand, in response to dark conditions, another center of the brain called the pineal gland gets involved.

The pineal gland releases melatonin. You can think of melatonin as the sleep hormone! Typically, melatonin starts to be released by the pineal gland 2-3 hours before bed. This is how your body normally prepares for sleep– however, environmental stimuli can greatly affect this.

Altering Circadian Rhythm

As alluded to above, your circadian rhythm can be drastically altered by exposure to natural and artificial light. This shifts your internal clock later, leading to the delayed release of melatonin and poor sleep quality. Additionally, as it gets closer to bedtime, our bodies become more and more sensitive to light’s effects on the circadian clock.

Several factors impact how much of an effect light will have on our bodies’ natural rhythms. This includes light intensity, wavelength, duration, and timing.

• Intensity is related to how bright the light is, measured in units called Lumen. The brighter a light source, the more impact it has.
• Wavelength relates to color and is measured in nanometers (nm). Humans can see between 380nm and 800nm. The blue light around 480nm has been shown to have the greatest effect on altering the circadian rhythm.
• Duration is related to how long a person is exposed to light. The more time you spend in front of an electronic screen or working under a desk light, the greater the impact.
• Timing is when you are exposed to light during a 24-hour day. Exposure to light later in the evening has a greater effect on shifting your circadian clock.

According to a study by the National Sleep Foundation (2011), approximately 90% of Americans surveyed reported using technological devices with artificial light before bed. In other words, most of us are altering our circadian rhythms without even knowing it!

Social Jet Lag

Another interesting concept discussed in this lecture is social jet leg. Social jet lag is defined as a shift in the midpoint of sleep between work days compared to days off. For example, on the weekends you may go to bed later and wake up later than your typical workday. This behavioral shift in the circadian clock can be detrimental to your health.

Multiple researchers have studied the impact of social jet lag on our health. For a social jet lag at, or greater than, 2 hours, it has been associated with:

• Increased depression
• Increased use of alcohol, nicotine, and caffeine
• Increased weight for those already overweight
• Increased resting heart rate
• Increased hemoglobin A1c (associated with diabetes risk)
• Increased C-reactive protein (associated with inflammation in the body)
• Decreased high-density lipoprotein (Otherwise known as HDL, which is your body’s “good cholesterol level”)
• Increased triglycerides (one form of “bad cholesterol” associated with blood sugars)

With similar effects associated with the environmental shift in circadian rhythm, it is clear to see that sleep schedule maintenance is important to our health. In medical circles, sleep is often described as a pillar of health similar to exercise and nutrition.  

Evidence-Based Recommendations

At this point, you now know about the effects of light and shifting sleep schedules on circadian rhythms. If you want to maximize healthy sleep, then there are some simple steps that you can take to improve your body’s natural rhythms. Although these may be simple, they are not easy. Some require a shift in lifestyle that will take practice and rearranging your schedule. It means prioritizing sleep!

Tips to Improve Your Sleep

• Develop and maintain a consistent sleep schedule.
  • Go to bed and wake up at the same time both on weekdays and weekends. Set a bedtime alarm to remind you to get ready for bed.
  • Try to get at least 7 or 8 hours of sleep a night.
• Get exposed to light during the day.
  • Sit by a sunny window or go outside to sit or walk. Try to get light in the morning, especially to help shift your sleep schedule to encourage melatonin release earlier at night. Try to get 30 to 60 minutes of exposure a day,
  • Try to avoid wearing sunglasses with light exposure, as this will filter out 90% of incoming light from reaching important photoreceptors.
• Minimize light exposure after sunset.
  • Dim your lights in the home. Use dimming features on personal electronic devices. Have a greater distance between electronic devices and your eyes. Avoid using any electronic devices 1 hour before bedtime.
  • Use light-blocking shades to keep your sleep environment dark.

There are two other ways to align with your natural circadian rhythms and improve your sleep.

The first is using blue-blocking glasses. This will block out specific wavelengths of light that have a greater impact on circadian rhythms. These can be very inexpensive investments.

The second is to use a lightbox in the morning. This will help shift the release of melatonin earlier at night, which encourages quality sleep. Lightbox therapy should not be used too early in the morning. According to Dr. Burgess’ research, most people should not use a lightbox before 8:00 am.

Dr. Burgess’ lecture was bursting with information. Below are a few more facts that she shared that are interesting. I highly encourage watching this lecture to learn more!

Interesting Health Facts

• Melatonin has anti-inflammatory properties.
• Bright light exposure (during the day) increases serotonin in the brain related to moods.
• Elderly persons may be the exception to evening light exposure. The elderly may fall asleep earlier than normal. Evening light exposure may help these individuals shift their sleep schedule later in the night.
• Morning light exposure reduced seasonal depression.
• Light box therapy may be helpful to reduce pain for those suffering from fibromyalgia and back pain.

Citation

Burgess, H., (2020, June 30). Lighting Up Our Lives: How Light Influences Our Mental and Physical Health [Lecture Recording]. NCCIH Integrative Medicine Lecture Series. https://videocast.nih.gov/watch=37830

Disclaimer

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