As a follow up to our recently published The Gut-Sleep Connection series, we’ll now explore Why We Need Sleep and What Regulates It.
Why Do We Need to Sleep?
When we hit the pillow at night, we may perceive sleep as a resting period, but for the brain and the body, it’s a very complex, metabolically active time. All aspects of our being – systems, organs, tissues, mind – are supported or compromised based on how much and how well we sleep. Sleep is designed to restore, recalibrate, renew, and upgrade brain and body functions.
From the perspective of the brain, sleep aids in problem-solving, influences memory retention and the ability to concentrate, regulates emotions, improves coping skills, and inspires creativity (Lewis, Knoblich & Poe 2018; Vandekerckhove & Wang 2018). In the body, sleep boosts immunity, balances metabolism and hormones, regulates blood sugar levels, manages blood pressure, combats fatigue, and suppresses cancer cell growth (Ibarra-Coronado et al. 2015; Irwin 2015; Schmid, Hallschmid & Schultes 2015).
The physiological processes behind all of these actions require being asleep. In a growing number of studies, the consensus is that the less we sleep, the higher our rate of diseased states and the shorter our life span. That explains why sleep determines health and quality of life.
What Regulates Sleep?
The two main factors regulating sleep are circadian rhythm and sleep drive. Both of these factors are linked to the gut, specifically the microbiome and the food choices we make. The first is our internal biological clock – called the suprachiasmatic nucleus – which creates our circadian rhythm. This internal rhythm, which has a cycle of roughly 24 hours, helps stimulate wake-sleep periods and is highly influenced by the environment, particularly light exposure. Beyond regulating wakefulness and the desire to sleep, circadian rhythm plays a role in determining body temperature, hormone secretions, metabolic rate, emotional state, appetite and digestive function.
The second is our sleep drive. During our wake cycle, the chemical adenosine is released and acts as a barometer of how long it’s been since we last slept. The chemical accumulates in response to increased energy consumption and metabolic activity from the day’s events. After an average of 12-16 hours of wakefulness, adenosine decreases alertness and eventually brings on a desire to sleep (Bjorness & Green 2009; Huang, Urade & Hayaishi 2011; Walker 2017). The combination of an internal chemistry shift and our circadian rhythm interacting with environmental cues helps regulate the timing of sleep and when we wake the next morning. These factors not only lead to sleep but launch a well-orchestrated sequence of events once it begins.
In our next part, we will look deeper into WHAT HAPPENS DURING SLEEP and WHEN WE’RE SLEEP DEPRIVED.
References from IDEA Fitness Journal March-April 2020 “The Gut-Sleep Connection” by Teri Mosey, PhD