The common belief that “sleeping off a high” is a simple method for achieving sobriety overlooks the complex biological processes governing drug elimination. When a person falls asleep while intoxicated, the drug remains active in the body, even if the mind temporarily ceases to register the full extent of the impairment. The duration and intensity of a drug’s effect are determined by its chemical structure and the speed at which the body’s metabolic machinery can break it down. This process, known as pharmacokinetics, continues regardless of whether a person is awake or asleep.
The Science of Drug Clearance During Sleep
The body’s primary mechanism for detoxification is the liver, which utilizes specialized proteins known as cytochrome P450 (CYP) enzymes. These enzymes are responsible for metabolizing approximately 75% of all drugs, transforming fat-soluble compounds into water-soluble metabolites that can be excreted through urine or bile. The speed at which the drug is processed is characterized by its half-life, which is the fixed amount of time required for the concentration of a substance in the blood to decrease by half.
Sleep does not accelerate this fixed metabolic rate; in fact, it may slightly slow it down. During sleep, physiological functions like heart rate and blood pressure decrease, which can lead to a slight reduction in hepatic blood flow to the liver. Since drug metabolism depends on blood flow, this reduction means the clearance process is not sped up and may even be marginally slower than during waking hours.
Circadian rhythms also influence drug elimination, a field of study called chronopharmacokinetics. Hepatic blood flow, for example, is highest in the morning, suggesting that the liver’s capacity to clear certain substances may be reduced during the night.
Physiological Risks of Sleeping While Impaired
Attempting to sleep while significantly impaired introduces several immediate, life-threatening dangers, particularly when central nervous system (CNS) depressants are involved. Substances like alcohol, opioids, and sedatives slow down the activity of the brain and spinal cord, which can lead to respiratory depression. This is a condition where the breathing rate becomes dangerously slow or shallow, and the risk is heightened during sleep when a person is unable to monitor their own condition.
Intoxication also severely impairs protective reflexes, most notably the gag reflex. Aspiration, which is the inhalation of vomit or stomach contents into the lungs, becomes a significant danger when a person is heavily sedated and vomiting occurs. If the gag reflex is suppressed, the individual cannot clear their airway, leading to potential choking, lung damage, or a severe infection called aspiration pneumonia.
A further risk is positional asphyxia, where a person is unable to move out of an unsafe position that restricts their breathing. Intoxication impairs the cognitive responses and coordination necessary to shift the body when the chest or diaphragm is compressed or the airway is occluded. When heavily impaired, an individual may pass out in a position that compromises respiration, such as face down or with their neck severely bent, and lack the motor control to correct it.
How Sleep Affects the High and the Wake-Up
While a person is asleep, the brain is deprived of external stimuli, which temporarily masks the subjective feeling of being intoxicated. This sensory deprivation creates the illusion that the effects are wearing off faster than they actually are. The intoxicating effects are still present at a cellular level, but the subjective perception of the high is temporarily dampened.
In reality, psychoactive substances significantly disrupt the normal structure of sleep, leading to poor quality rest. Many drugs, including stimulants and cannabis, interfere with the cycling between non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. This disruption often manifests as decreased REM sleep and reduced slow-wave sleep, which are the most restorative stages of the sleep cycle.
Waking up from this chemically-altered sleep often results in a prolonged period of grogginess or a “hangover” effect because the brain has not completed its necessary restorative processes. Even if the person feels somewhat rested, residual impairment in cognitive function and motor skills can still be present. This lingering effect means that activities requiring coordination and judgment, such as driving, remain unsafe long after the subjective feeling of the high has disappeared.