How Aging Affects Your Circadian Rhythm

You may have noticed as you’ve gotten older that both the quality and the quantity of your sleep has decreased significantly.

You’re not alone. Insomnia is more common in older adults and seniors than in any other age group. Chronic insomnia is an issue that 42 percent of people over the age of 60 have reported sleep complaints, according to a 1995 study by the National Institute of Health. A 2017 poll indicated similar numbers.

There are two types of insomnia: primary and secondary insomnia. Primary insomnia is caused by a problem that occurs only or mainly during sleep, like restless leg syndrome, sleep apnea and or periodic limb movement disorder. Primary insomnia is likely to be diagnosed by a sleep study.

Secondary insomnia is the result of environmental factors like side effects from medication or blue spectrum light from electronic devices, according to the New York Times. Secondary insomnia is much more common since there are a lot more possibilities. To decrease the likelihood of environmental factors affecting your sleep, you can make some changes to your bedroom. Blackout curtains, an upgraded mattress, and a window fan all may be able to help you sleep easier. However, the aging of your eyes might be part of the problem that causes secondary insomnia, according to researchers from the University of Kansas Medical School.

Your circadian rhythm, colloquially known as your internal clock, relies on light to function properly. In 2002, researchers discovered a new type of receptor in the retina, called retinal ganglion cells. These cells are especially receptive to blue light, which is especially effective at suppressing the release of melatonin, one of the hormones that make you feel sleepy.

Studies show that people who have off-kilter internal clocks are more susceptible to all kinds of illnesses, including heart disease and cancer. In a study in The British Journal of Ophthalmology, it was discovered that the receptors in the eye of an adult receive just 50 percent of the light needed to stimulate the circadian system fully. By age 55, the amount of light drops to 37 percent, and by age 75, to 17 percent. That is because as you age, your eyes gradually get more yellow, and your pupils narrow.

In short, as your eyes age, they take in less and less light, meaning that your body doesn’t can't tell if its daytime or nighttime as easily. That lowered level of light being transmitted to your brain means that your body doesn’t produce as much melatonin as it used to in the evenings, meaning you don’t get tired at the right time. You’ll get tired during the day, or have a sleep hangover where you feel like you can’t wake up.

Swedish researchers found that patients who had cataract surgery had significantly reduced rates of both insomnia and daytime sleepiness. “Interactions are complex, but light deficiency may be a common causative factor,” the conclusion reads.

So, if you want to improve your sleep, find some blue light during the day to sync your circadian rhythm. If you have a tablet or cell phone, video call your kids and grandkids. The blue light will do you good.