What is the Relationship Between Sleep and The Circadian Rhythm?

We all like sleep. It’s one of those things we all need and we all like and literally can’t live without. There is little as satisfying as a good night’s sleep – unfortunately many do not get a “good night’s sleep”. According to this article from the CDC 1 in 3 American adults don’t get consistently good sleep. 

There are a number of causes of bad sleep, from stress to drinking to crappy beds to crying babies. But one important element of healthy sleep that is not commonly thought of is something called the Circadian Rhythm.

The Circadian Rhythm is a natural, internal process that regulates the sleep-wake cycle and various bodily functions in living organisms, including humans. It’s often referred to as the “body clock” because it orchestrates a 24-hour cycle of physiological and behavioral changes, influenced primarily by the light-dark cycle of the Earth’s rotation. It’s been a natural part of human existence since the beginning of time and is essential for maintaining optimal functioning of the body, including sleep patterns. 

However, with the advent of indoor lighting over the last 100 years we have unnaturally changed the way our bodies interact with light, and as a result our circadian rhythm has been impacted greatly.  This article explains some of the effects modern lighting has had on our sleep patterns. 

Key points about the Circadian Rhythm and its effects on sleep:

Sleep-Wake Cycle Regulation: The Circadian Rhythm helps synchronize the body’s sleep-wake cycle with the external environment. It signals when it’s time to be awake and alert and when it’s time to sleep. The internal clock is primarily controlled by a region in the brain called the suprachiasmatic nucleus (SCN), located in the hypothalamus.

Light and Melatonin: Light is the primary external cue that helps regulate the Circadian Rhythm. The retina in our eyes contains specialized cells called photoreceptors that detect light and send signals to the SCN. When light is detected, the SCN signals the pineal gland to reduce the production of the hormone melatonin. Melatonin is often called the “sleep hormone” because its levels rise in the evening, promoting drowsiness and facilitating the onset of sleep.

Sleep Phases: The Circadian Rhythm influences the different phases of sleep. There are two main types of sleep: Rapid Eye Movement (REM) sleep and Non-Rapid Eye Movement (NREM) sleep, which is further divided into stages 1, 2, and 3. These sleep stages follow a distinct pattern throughout the night due to the fluctuations in melatonin and other hormones.

Body Temperature and Alertness: The Circadian Rhythm also affects other bodily functions, such as body temperature and alertness. Body temperature tends to be higher during the daytime and lower during the nighttime. This temperature variation contributes to feelings of wakefulness during the day and sleepiness at night.

Jet Lag and Shift Work: Disruptions to the Circadian Rhythm can lead to issues like jet lag and difficulties in adjusting to shift work. Traveling across multiple time zones quickly can result in a misalignment between the internal clock and the new local time, causing sleep disturbances and general discomfort.

Individual Variations: While the average Circadian Rhythm follows a roughly 24-hour cycle, there are individual variations. Some people naturally have a preference for being more active and alert in the morning (morning larks), while others are more alert in the evening (night owls). These differences are partly influenced by genetics.

Blue Light Impact: Artificial light and the increasing use of electronic devices with screens emitting blue light, such as smartphones and computers, can disrupt the Circadian Rhythm. Blue light exposure in the evening can suppress melatonin production, delaying the onset of sleep and potentially leading to sleep problems.

In summary, the Circadian Rhythm plays a crucial role in regulating our sleep-wake patterns and influencing various physiological processes. Maintaining a regular sleep schedule, exposing yourself to natural daylight during the day, and minimizing blue light exposure in the evening can help optimize your Circadian Rhythm and improve your sleep quality.

Does the lighting in my home impact the Circadian Rhythm?

Yes, the lighting in your home can significantly impact your circadian rhythm and overall well-being. The type, intensity, and timing of the lighting you’re exposed to can influence your body’s internal clock, sleep patterns, mood, and overall health. Here’s how:

Color Temperature: The color temperature of light refers to how “warm” or “cool” it appears. Light sources with higher color temperatures, such as daylight and cool white LED lights, emit more blue light. Exposure to blue-rich light during the daytime can help regulate your circadian rhythm by signaling to your body that it’s daytime and promoting alertness.

Evening Lighting: As the evening approaches, it’s beneficial to reduce your exposure to blue-rich light. Blue light exposure in the evening can disrupt your circadian rhythm by suppressing melatonin production, making it harder to fall asleep and impacting sleep quality. Using warmer, dimmer lights in the evening can help signal to your body that it’s time to wind down and prepare for sleep.

Bedroom Lighting: The lighting in your bedroom is particularly important for sleep. Use soft, warm lighting before bedtime to create a relaxing atmosphere. Avoid bright overhead lights and opt for bedside lamps with lower intensity. If you need to get up during the night, use dim, red nightlights, as red light has a lesser impact on melatonin production.

Natural Light Exposure: Exposure to natural daylight during the day is crucial for maintaining a healthy circadian rhythm. Spend time outdoors or open your curtains to let in natural light. This helps regulate your internal clock and improve sleep quality.

Artificial Light Sources: Different light sources emit different spectrums of light. Traditional incandescent bulbs emit warmer light, while LED and fluorescent lights can vary in color temperature. Some modern LED lights are designed to mimic natural daylight, which can be useful during the day but should be avoided in the evening.

Lighting Control: Consider using smart lighting systems that allow you to adjust the color and intensity of your home lighting based on the time of day. Many of these systems have settings that automatically shift from cooler, brighter light during the day to warmer, dimmer light in the evening.

Blue Light Filters: If you can’t avoid using electronic devices with screens in the evening, use blue light filters or “night mode” settings to reduce the amount of blue light emitted.

In summary, paying attention to the lighting in your home, especially in the evening hours, can help you maintain a healthy circadian rhythm and improve your sleep quality. Creating a lighting environment that supports your body’s natural sleep-wake cycle can have positive effects on your overall well-being and daytime performance.

What can you do about it?

This all might sound a little dire, but it isn’t all doom and gloom. There are a number of things you can do to help improve your sleep quality and circadian rhythm:

1. Get off your phone and TV before you go to bed – this is tough because it’s so easy to just scroll away on your phone while in bed. This writer is particular notorious for needing to watch nature documentaries prior to sleep (David Attenbourough starts speaking and I immediately knock out). However reducing consumption of these blue light intensive devices will help.
2. Change Your Lighting – If your health and sleep quality is important to you, it might make sense to make the investment in a smart lighting technology like HomeGlo. Our system has been built to transform your home into a sanctuary that changes brightness, hue and intensity over the course of the day and has been designed precisely to help improve mood and sleep quality through lighting.