Circadian Rhythm & Sleep

Posted by on Jun 1, 2017

Did you know that our bodies come fully equipped with an internal clock? Just below the brain, there is a cluster of about 20,000 nerve cells known as the suprachiasmatic nucleus (SCN). The SCN is connected to various parts of the brain and it acts as a control center for certain bodily functions. It helps regulate sleep and wakefulness, body temperature, and various hormonal changes during a 24-hour cycle. Let’s take a closer look to understand how this works!

How Does The SCN Work?

The SCN is responsible for determining the beginning and the end of each 24-hour cycle. From the first moment that light enters your eyes, the SCN begins to relay time-of-day information to your brain. Due to its proximity to the optic nerve, the SCN interprets information about incoming light. As light increases with the rise of the sun, the SCN signals the brain to promote alertness even before you’re awake. Similarly, as light in our environment begins to dim as the evening approaches, the SCN sends nerve signals to initiate body relaxation, decrease alertness, and begin sleep.

How Does The SCN Help Regulate Sleep?

At night, when sunlight vanishes from the sky, the SCN also promotes sleepiness. It does so by stimulating the secretion of a special hormone in the pineal gland called melatonin. Melatonin is a naturally occurring hormone associated with sleep onset. As melatonin levels peak, it induces drowsiness, drops your body temperature, and you begin to feel less alert. Thus you body becomes more suitable for sleep. During the day, melatonin levels remain somewhat negligible until the start of a new day.

How Does Blue Light Affect Your Sleep?

Blue light is everywhere. Sunlight contains blue light as part of its spectrum. As sunlight  passes through the atmosphere, blue light waveforms scatter giving our skies its beautiful blue color. In its natural form, your body uses natural blue light to boost alertness and stay awake during the day. This is a desired effect as it’s an integral part of our circadian rhythm. However, blue light also exists in artificial sources. These include, electronic devices such as cell phones and laptop computers, as well as energy-efficient fluorescent bulbs and LED lights.

Prolonged exposure to artificial blue light causes your brain to suppress melatonin, thus disrupting your circadian rhythm by stimulating wakefulness beyond the evening hours. Circadian rhythm disruptions are known to cause to medical issues like depression, obesity, breast and prostate cancer, and cardiovascular disease. It’s even associated with sleep disorders like insomnia and delayed phase sleep disorder. Therefore, staring at blue light emitting devices before going to bed should be avoided.

Things To Consider

If you struggle falling asleep, consider the following tips: First, make sure that you get plenty of daylight. Researches have found that plenty of daylight during wake hours helps promote your body’s desire to rest at night. Should you spend most of your days indoors, schedule times to be outside, perhaps take walks if you can. At night, don’t wait until it’s time to go to bed to turn off the lights. Possibly, install light dimmers to gradually turn your house into an environment for sleep. Prolonged exposure to artificial light at night can prolong wakefulness to undesired times.