Understanding Circadian Clock Disruption

This is part two of a series on optimizing sleep. If you haven’t already ready Sleep Basics, you can check it out in the Articles section.

Picking up where we left off last, let’s look again at the significance of circadian clock disruption.

Circadian clock disruption refers to a misalignment of the body’s internal 24-hour biological rhythms with external environmental cues, primarily the light-dark cycle. When this rhythm is interrupted or broken, it affects various physiological processes, including hormone production, body temperature regulation, cell regeneration, and most importantly, the body’s ability to rest and restore itself, absorb nutrients, and stay in homeostasis. Shift work, travel across time zones, and exposure to artificial light at night can all undermine your circadian clock.

On the other hand, sleep cycle disruptions specifically relate to disturbances in the pattern of sleep stages throughout the night.

Common sleep problems, including:

• frequent awakenings
• difficulty falling asleep or
• problems maintaining sleep

are all indications of sleep cycle disruptions that can be caused by any number of factors:

• stress
• illness
• alcohol or substance use
• hormonal changes
• environmental disturbances

When it comes to trying to achieve high-quality sleep on a regular basis as a foundation to optimal metabolic functioning, it can help to understand the mechanisms and adverse effects of circadian clock disruption.

Impact of Circadian Clock Disruption on Cell Metabolism

Circadian clock disruption significantly impacts cell metabolism through various mechanisms including glucose and fat metabolism, overall energy homeostasis, and overall circadian gene expression.

In terms of glucose metabolism, a disruption in the circadian clock reduces insulin sensitivity and increases insulin resistance; impairs glucose tolerance; and leads to hyperglycemia and hypoinsulinemia.

Disruption of this sleep mechanism also alters lipid metabolism by causing hyperlipidemia (i.e., elevated triglycerides) and disrupts phospholipid metabolism, including phosphatidylcholine and circadian gene expression.

Further circadian clock disruption promotes hyperphagia, accelerates weight gain, and alters metabolic hormone levels. At the genetic level, such disruptions also affect the rhythmic expression of clock-controlled genes. Collectively, these metabolic disruptions further increase the risk of metabolic disorders such as obesity, type 2 diabetes, and metabolic syndrome.

Specifically, type 2 diabetes is closely associated with this loss of circadian rhythmicity because of the related impairment of glucose metabolism; pancreatic beta cell dysfunction that creates more oxidative stress; disruption of glucose and lipid metabolism in the liver; and dysfunction in the hypothalamic-pituitary-adrenal (HPA) axis that then leads to the dysregulation of glucocorticoid levels.

These disruptions collectively impact overall homeostasis and downregulate redox balance.

There’s one intervention that can help restore the body’s clock: exercise!