Drinking soda before bedtime is detrimental to quality sleep. Soda refers to carbonated beverages high in refined sugar and often containing stimulants like caffeine. These drinks contain multiple components that disrupt the body’s natural transition into a restful state.
Caffeine and Sugar Effects on Sleep Onset
Many popular sodas contain caffeine, a powerful central nervous system stimulant that actively works against the body’s natural sleep signals. This compound functions by binding to adenosine receptors in the brain, effectively blocking the action of adenosine, which is a chemical that builds up throughout the day to create “sleep pressure.” By preventing adenosine from signaling fatigue, caffeine keeps the brain in a state of wakefulness, making it harder to initiate sleep.
Caffeine has a relatively long half-life, meaning the time it takes for the body to eliminate half of the consumed amount is typically between four and six hours. If a person consumes a caffeinated soda six hours before lying down, a substantial amount of the stimulating compound is still actively circulating. Consuming caffeine this late in the day can delay the onset of sleep by hours.
The high sugar content in many sodas presents a second challenge to sleep initiation. When a large dose of refined sugar is consumed, it leads to a rapid spike in blood glucose levels. This sudden influx of energy counteracts the body’s natural winding-down process, providing an unwanted burst of energy.
The body responds to this high glucose level by releasing insulin to move the sugar out of the bloodstream and into the cells. This physiological response is designed to regulate blood sugar, but the resulting metabolic activity is stimulating. This metabolic disturbance can keep the nervous system active, contributing to insomnia and making it difficult to relax enough to fall asleep.
Digestive System Distress from Acidity and Carbonation
Soda introduces physical and chemical irritants into the digestive system that can directly cause discomfort and prevent restful sleep. Most sodas, including many diet versions, are highly acidic due to ingredients like phosphoric acid, citric acid, and carbonic acid. Lying down soon after ingesting an acidic beverage increases the risk of acid reflux, or heartburn.
This backward flow of stomach contents can trigger a painful burning sensation in the chest and throat, a condition known as Gastroesophageal Reflux Disease (GERD). The acidic nature of the drink can also relax the lower esophageal sphincter (LES), the muscle that acts as a barrier between the stomach and the esophagus, further enabling reflux. Nighttime acid reflux is disruptive to sleep quality, often causing abrupt awakenings.
The carbonation in soda, which is carbon dioxide gas dissolved under pressure, contributes to physical discomfort. Once the soda is consumed and warms up in the stomach, this gas is released, causing the stomach to distend. This distension can lead to feelings of uncomfortable fullness, bloating, and increased abdominal pressure.
Bloating makes it challenging to find a comfortable sleeping position and can cause restlessness as the body attempts to expel the trapped gas. The physical sensation of pressure and discomfort acts as an internal irritant, making it difficult to settle into the stillness required for deep sleep.
How Diuretic and Metabolic Effects Fragment Sleep
Once a person manages to fall asleep, the components of soda can continue to interrupt rest through two distinct mechanisms that cause sleep fragmentation. The first is the diuretic effect of both the liquid volume and the caffeine content in the soda.
Caffeine is a mild diuretic that stimulates the kidneys to increase urine production. Consuming a large volume of liquid combined with this diuretic effect right before bed increases the likelihood of nocturia, the need to wake up during the night to urinate. These forced awakenings disrupt the natural sleep cycle, pulling the person out of deeper, restorative stages of sleep.
The second mechanism is the metabolic rebound that occurs hours after the initial sugar spike. The high insulin release triggered by the soda’s sugar content can eventually cause blood glucose levels to drop too rapidly or too low, leading to reactive hypoglycemia. The body interprets this sudden drop in blood sugar as a physical stressor.
In response to this perceived emergency, the body releases stress hormones, primarily cortisol and adrenaline, to prompt the liver to release stored glucose. These hormones are designed to wake and alert the body. Their release can cause abrupt, middle-of-the-night awakenings or a period of restless, poor-quality sleep.