We have discussed many times how getting good sleep is vital for good health. However, many people often claim to feel exhausted during the day, but awake at night, unable to sleep. There are, of course, many explanations for this––too much caffeine, stress, or other factors can contribute to fatigue, or restlessness. But one simple, often-overlooked factor might be an out of balance circadian rhythm.
Circadian rhythm refers to the 24-hour biological cycle that regulates various physiological and behavioral processes in living organisms, including humans. It is primarily influenced by environmental cues, but light is the most potent signal for regulating the circadian system. The human circadian rhythm is primarily regulated by a master clock located in the brain called the suprachiasmatic nucleus (SCN), which is sensitive to light. Light exposure, particularly the presence or absence of natural daylight, plays a vital role in synchronizing the circadian rhythm with the external environment.
The relationship between light viewing and circadian rhythm is crucial and intertwined; light exposure, particularly in the blue spectrum, suppresses the secretion of melatonin, a hormone that helps regulate sleep-wake cycles. When exposed to bright light, especially in the morning or during the daytime, the SCN sends signals to the pineal gland to inhibit melatonin production, promoting wakefulness and alertness.
Conversely, in the absence of light, such as in the evening or during nighttime, melatonin production increases, signaling the body to prepare for sleep. This mechanism helps maintain a regular sleep-wake schedule aligned with the natural light-dark cycle.
These are natural cues that help our bodies know when it is time to be awake, alert and energized, and when it is time to get sleepy and go to sleep. Obviously, when these things are out of alignment, we might not get the rest we need, or feel the energy needed to get through the day. So what can disrupt this natural cycle?
Artificial light sources, such as electronic devices and indoor lighting with high levels of blue light, can disrupt the natural circadian rhythm. Prolonged exposure to these sources, especially in the evening or close to bedtime, can suppress melatonin production and delay the onset of sleep.
To support a healthy circadian rhythm, it is important to maintain a balance of light exposure throughout the day. Spending time in natural daylight, especially in the morning, can help synchronize the circadian rhythm and promote wakefulness. Additionally, minimizing exposure to bright artificial light and blue light, particularly in the evening, can aid in the natural production of melatonin, facilitating a better night’s sleep. And stop looking at screens late in the evening; at the very least, put them in blue light mode.
The relationship between light viewing and circadian rhythm is reciprocal. Light exposure, particularly in the blue spectrum, helps regulate the circadian rhythm, promoting wakefulness during the day. Conversely, limited exposure to bright light, especially in the evening, allows the natural production of melatonin, facilitating sleep onset and a healthy sleep-wake cycle.