Circadian rhythm, sleep and overeating

Circadian rhythm is what keeps our bodies functioning properly. It dictates the timing of natural processes to keep a healthy body. For example, sleep plays a crucial role in our health because our brains and bodies are actively repairing when we are sleeping.

There is an important link between sleep and nutrition. Not sleeping enough impacts our ability to regulate our emotions, appetite and food choices, which increase the likelihood of both overeating and consuming unhealthy foods. On the other hand, poor food choices during the day may affect how well we sleep.

Understanding the connections between sleep and nutrition creates opportunities to optimize both to eat smarter, sleep better, and live healthier lives.

Let’s get started!

Let’s talk about circadian rhythms

Circadian rhythms are physical, mental, and behavioural changes that follow a 24-hour cycle. Different body systems, such as the digestive, circulatory and immune systems, follow circadian rhythms synchronized with a master clock located in a part of the brain called the hypothalamus.

The circadian rhythms ensure that all body’s processes, like sleep and digestion, are optimized during the day. These natural processes respond to exercise, social activity, and temperature, but the light is the most powerful influence on circadian rhythms.

Exposure to light at night perturbs the circadian system because the light is the major entraining cue used by the body to discriminate day from night.

The clocks react to cues such as food or light and communicate with one another throughout the day to decide what to do. For example, if there is light, the master clock will send a message to all the clocks to “wake up is time to be active” if it is dark, it will be more like “chill out and yoga time everybody”, but if we are under stress at night time, the clock will send a message to “stay awake and alert”.

But our modern life has provided us with artificial sources of night-time light like television and smartphones. These electronic devices, and much of the inside lighting we use in our homes, emit high-intensity blue light that gets misinterpreted as daylight.

The problem?

When our exposure to light is nearly constant, biological and behavioural rhythms can become desynchronized, leading to negative consequences for our mental and physical health. Based on these messages, your brain sends instructions to either produce or suppress your body’s sleep-promoting hormone, melatonin.

When our sleep is compromised or we experience sleep disturbance, this will negatively impact our hormonal rhythms and metabolism. Also, this is associated with obesity, insulin insensitivity, diabetes, hormonal imbalance, and appetite dysregulation.

The connection between sleep and overeating

As we saw before, sleep disturbance will negatively impact hormonal rhythms. This disruption to normal hormone production is a driving factor behind sleep deprivation leading to overeating.

The hormones leptin (tied to feeling full) and ghrelin (related to hunger) both are integral to hunger and appetite are affected by sleep disruptions because a lack of sleep increases levels of ghrelin and decreased levels of leptin, affecting parts of the brain that determinate how we think about food; In other words, it makes us more hungry and vulnerable to overeating. https://pubmed.ncbi.nlm.nih.gov/22357722/ https://pubmed.ncbi.nlm.nih.gov/15583226/

At the same time, overeating can affect sleep. Because apart from making you feel too full, big meals may cause and increase acid reflux production, affecting good quality sleep. But it is not only about how much or what you eat; timing matters too. For example, eating close to bed will increase the changes in acid reflux, and negativity impacts metabolism.

How to maintain a healthy circadian rhythm?

  • Sun exposure
  • Consistent sleep schedule
  • Exercise and movement during the day
  • Keep naps short and early in the afternoon to avoid disrupting sleep in the evening.
  • Avoid caffeine after 2:00 pm.
  • Consume most of your calories during the day and eat your last meal at least two hours before bedtime
  • Limit blue light before bed (at least an hour before bedtime)
  • Reduce stress levels, especially before bedtime

(more about sleep, go to my 5 tips to a better sleep article)

Bottom line:

Unfortunately, circadian rhythm disruptions are common in our modern society, with most people eating late meals, checking social media before going to bed and working at night.

Whatever you are dealing with, overeating or not keeping a healthy circadian rhythm and sleep hygiene is crucial for your body processes and overall health. So take sleep seriously and get blue blockers glasses already!

Resources:

https://pubmed.ncbi.nlm.nih.gov/25450058/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3763921/

https://pubmed.ncbi.nlm.nih.gov/22259064/

https://pubmed.ncbi.nlm.nih.gov/25861266/

https://www.nature.com/articles/s41398-020-0694-0

https://www.nature.com/articles/s41398-020-0694-0

https://pubmed.ncbi.nlm.nih.gov/11583769/

https://pubmed.ncbi.nlm.nih.gov/28164452/

https://pubmed.ncbi.nlm.nih.gov/17212793/

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