As a follow up to our recently published The Gut-Sleep Connection series, we’ll now explore How Gut Health Plays a Part, How Sleep Manages Appetite and Metabolism, and Eating Strategies for Improved Sleep.
How Does Gut Health Play a Part?
The gut goes beyond its mechanical role of digesting food and extracting energy. Also known as the enteric nervous system, the gut regulates mood, behavior, emotions and higher cognitive function. As research continues to uncover these connections, we are identifying practical lifestyle actions with the gut as a starting point.
Three aspects of the complex digestive system pertain to the gut-sleep connection.
1. The gut has its own brain, nervous system and ability to work independently of the neocortex (rational or thinking) brain. This gut-brain regulates immunity, coordinates neurotransmitter and hormone secretions, influences emotions, affects threshold sensitivity to pain, and supports decision-making and sleep patterns (Liu & Zhu 2018; Rosselot, Hong & Moore 2016; Wu & Wu 2012).
2. Seventy percent of the cells that provide our immunity reside in the gut. They’re part of the gut-associated lymphatic tissue, or GALT. Immunity extends past the expected role of a defense system against viruses, bacteria or foreign pathogens. Immunity has a hand in mood, emotions, circadian rhythms and the ability to sleep deeply.
3. The Human Microbiome Project has taken an extensive look into the hundred trillion microbes that live throughout the body, with a special focus on the 4 pounds found in the gut. This microbiome, composed of a thousand different types of bacteria, is unique to each one of us. It participates in nutrient absorption, the learning process, immune responses, coping abilities, state of mind and sleep patterns.
The microbiome has its own internal rhythm or clock, just as the body is governed by a circadian rhythm. These two rhythms are intertwined and work together to manage digestion, immunity, brain chemistry and sleep (Voigt et al. 2016; Wang et al. 2017). Each of the different microbes produces specific neurotransmitters, immune cytokines, and metabolites such as serotonin, dopamine, GABA (gamma-aminobutyric acid) and melatonin, all of which influence stages of sleep (Barrett et al. 2012; Li et al. 2018; Petra et al. 2015). When sleep deprivation throws off circadian rhythms, the composition of these microbes changes (Anderson et al. 2017).
Whether sleep deprivation is due to psychological stress, late-night shift work, inflammatory issues, jet lag or simply not making sleep a priority, there’s a direct connection between gut and brain. This connection is bidirectional. If the microbiome is not nurtured properly through eating and lifestyle actions, the change in microbe composition can initiate sleep deprivation. It works both ways.
Sleep Manages Appetite and Metabolism
Exploring the gut-sleep connection is another way to appreciate the holistic design of a human being. Everything about us is connected. How does sleep manage our appetite, metabolism and long-term weight management? It comes down to hormones.
When we’re sleep-deprived, there is a shift in many of the hormones that stimulate hunger and alter our metabolism. Two key players are ghrelin and leptin. Ghrelin, mainly a digestive hormone, communicates hunger so that we seek our next meal. It also plays a role in sleep by promoting the slow waves of deep NREM, the release of growth hormone and the regulation of insulin, which all support nighttime’s healing processes (Kim, Jeong & Hong 2015; Weikel et al. 2003).
Leptin, found in adipose tissue, regulates long-term energy balance and will suppress appetite to maintain a balance between eating and fasting. It communicates satisfaction with a meal, signaling it’s time to stop eating.
When this ghrelin and leptin duo is working effectively, we experience a healthy appetite, feel satisfied from our meals and maintain a fit weight. It’s another story when sleep loss disrupts the actions of these two hormones.
In times of insufficient sleep, ghrelin responds by increasing appetite along with creating sweet cravings, especially for fast-releasing carbohydrates such as bakery goods. When we’re tired, brain functioning shifts to more primitive regions, which affects decision-making. (You will have no problem eating an entire bag of chips or rationalizing a drive-through fast-food meal.) During sleep-deprived moments, leptin, which communicates satisfaction and removes the appetite signal, keeps the green light on. This results in overeating, less health-supportive food choices, eating that is influenced by emotions, and hormone activation that simultaneously slows metabolism and increases fat storage (Klok, Jakobsdittir & Drent 2007; Leproult & Van Cauter 2010; Taheri et al. 2004).
Ghrelin and leptin are the strongest influencers of this sleep-eating connection; however, research is currently bringing additional hormones – such as cortisol, adiponectin, insulin and endocannabinoids – into the conversation. Ultimately, less sleep shifts the entire hormone network to stimulate hunger and create cravings, leaving us unsatisfied and struggling with weight management. Take-home message.. make sleep a priority!
Eating Strategies for Improved Sleep
With a bidirectional gut-sleep connection, creating eating strategies to support the microbiome is a starting point for regulating and improving sleep patterns. This can be done through food selection, timing and the eating environment.
Eat a primarily plant-based diet. This recommendation is based on a few factors. First, plants contain phytonutrients, health-supportive compounds that boost antioxidant capacity and strengthen immunity (Eichelmann et al. 2016; Liu 2013; Tuso 2013). Immunity is one the three main pathways in the gut-sleep link. Eating a plant-based diet also creates a nutrient profile that is higher in complex carbohydrates and fiber and lower in saturated fats. Research is demonstrating that this combination decreases the number of nighttime arousals and supports longer periods spent in the deep NREM sleep stage (St-Onge, Crawford & Aggarwal 2018; St-Onge et al. 2016). Fiber, along with its immune system – boosting qualities, is a microbiome supporter, feeding friendly bacteria (Menni et al. 2017; Singh et al. 2017).
Researchers are finding that eating a primarily plant-based diet helps to regulate blood sugar levels and stimulate production of the neurotransmitters serotonin and melatonin, thereby calming the nervous system and helping us get to sleep and also stay asleep (Islam et al. 2015; Strasser, Gostner & Fuchs 2016). Brain-calming foods include oats, avocado, walnuts, pumpkin seeds, bananas, tomatoes, plums and seaweeds. As much as the research fascinates with its detail, however, do not overthink or overcomplicate food choices. This can just add additional stress and further affect sleep patterns. Simply shift to eating more plants, fruit, nuts and seeds.
Add small amounts of fermented foods. The gut-sleep connection is influenced by the number of friendly bacteria as well as the diversity of bacterial strains. This means that adding small amounts of fermented foods to our diet can boost sleep. Raw, unpasteurized, naturally fermented sauerkraut, tempeh, miso and apple cider vinegar are all options.
Minimize caffeine consumption. Remember the sleep drive and release of adenosine that regulate sleep? Caffeine, perhaps from a cup of coffee, blocks adenosine cell receptors and halts the communication that regulates the wake-sleep cycle. This temporarily increases dopamine and adrenaline so we feel more alert and motivated. Because caffeine blocks the receptors for adenosine, it accumulates in the bloodstream until the caffeine metabolizes, releasing the chemical process and resulting in an energy crash (Holford 2005).
This cycle of energy burst to exhaustion disrupts sleep. If you struggle with insomnia, avoid caffeine beverages, like coffee, until your sleep improves. Otherwise, drink a morning cup of coffee or other caffeine-infused beverage no less than 10 hours prior to bedtime. Ten hours is how long it takes to metabolize caffeine out of your system. While making this adjustment, pay attention to staying hydrated, as that also influences sleep quality.
Make dinner the smallest meal. It’s never just about the food. Everything about the eating experience affects the absorption and assimilation of nutrients and, more importantly, how food interacts with our entire being.. body and mind. One factor is the timing of meals. The body has internal physiological processes and cycles that happen at precise times of the day. Since the digestive system is most active during earlier parts of the day, lunch is ideally the largest meal and dinner the smallest. Consider a soup or snack for dinner no later than 7 p.m. in preparation for the body’s evening healing and restorative processes. This may shift socialization around meals, but that shift can lead to positive sleep patterns and, ultimately, a boost in health.
Add mindfulness to your eating experiences. Mindfulness alters the activation of the nervous system from SNS to PNS, which supports efficient digestion. Begin with conscious breathing prior to a meal, then eat more slowly with attention. Practicing being present and aware is associated with decreased inflammation and improved sleep (Fountain-Zaragoza & Prakash 2017; Pintado-Cucarella & Rodriguez-Salgado 2016).
Lifestyle Choices and Nutrition Aid the Gut-Sleep Connection
Sleep is a pillar of health and well-being, as it touches all aspects of body and mind. We can begin to improve our quality of sleep, decrease the onset of chronic illnesses and, perhaps, extend our life spans by beginning to nurture the gut-sleep connection. This begins with food choices and mindful eating and extends into our daily actions. The human design is holistic, with every system of the body connected, including the gut-sleep system. Seek out consistency in your eating and sleep routines to reap the benefits.
References from IDEA Fitness Journal March-April 2020 “The Gut-Sleep Connection” by Teri Mosey, PhD