Quality of Sleep in Children Influences Alcohol and Marijuana Use in Adolescence
Sleep deprivation in childhood can harm the neurological development of a child's brain (1).
Sleep is an essential biological process at all stages of life. During childhood, a significant amount of time is dedicated to sleep, which is crucial for proper physical development, strengthening the body's natural defenses against illness, and promoting overall quality of life and well-being (2). According to the Brazilian Sleep Association (BSA), good sleep is important at any age as it positively affects daily behavior, increasing concentration, memory, and learning abilities.
The pattern and amount of sleep needed vary according to the child's age. According to the BSA, infants aged 4 to 12 months need 12 to 16 hours of sleep per day. Children aged 1 to 2 years should sleep between 11 and 14 hours, while those aged 3 to 5 require 10 to 13 hours of sleep. For children aged 6 to 12 years, the recommendation is to sleep 9 to 12 hours per night. Unfortunately, sleep insufficiency is prevalent among children and adolescents, and the consequences are related to reduced development of the prefrontal cortex, which can impair decision-making skills (3,4,5).
One study showed that sleep loss in children is also associated with increased activation of the brain's reward centers, disproportionately increasing motivation for unhealthy behaviors, such as alcohol and marijuana use (6). Adolescent alcohol use has been linked to deficits in executive function, visuospatial function, short- and long-term memory, and working memory—consequences that can have significant implications for future life.
Although there is a lack of studies comparing the effects of childhood sleep at different developmental stages within the same sample of children, a recent study analyzed how sleep during weekdays in childhood can influence substance use in adolescence (7). The results showed that children who go to bed later during the week are more likely to use substances by age 15, while shorter sleep duration in late childhood was specifically associated with an increased risk of marijuana use in adolescence.
In light of this, it is essential to promote healthy sleep habits from childhood to prevent negative consequences in adolescence, including alcohol use, other psychoactive substances, and cognitive difficulties. Investing in education about the importance of sleep and creating appropriate routines can help ensure the healthy development of children, reducing the risks of future problems associated with insufficient sleep.
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How Alcohol Alters Sleep: Scientific Evidence on Its Effects on Sleep Architecture and Rest Quality
Consuming alcohol before bedtime is a common practice, often seen as a way to facilitate sleep. However, recent scientific evidence, including a systematic review and meta-analysis of 27 studies published in 2025, shows that alcohol can significantly alter sleep quality in healthy adults. Even if it appears to help with falling asleep, its effects throughout the night compromise essential restorative sleep cycles.
Alcohol acts as a central nervous system depressant, reducing the time it takes to fall asleep by promoting relaxation and drowsiness. However, its effects on sleep are not uniform across the night. Alcohol can significantly alter sleep architecture, mainly by reducing the duration of and delaying the onset of REM sleep—a sleep stage associated with memory consolidation, emotional regulation, and brain restoration.
A review study published in 2025¹ showed that even low to moderate doses of alcohol impair REM sleep and increase sleep fragmentation and awakenings during the second half of the night, when the body is metabolizing alcohol and its byproducts, such as acetaldehyde and acetate, which increase physiological activity and body temperature. High doses accelerate the onset of deep sleep (N3), but REM sleep disruption and persistent fragmentation remain, compromising overall sleep quality.
In addition, alcohol relaxes the muscles of the throat, increasing the risk of snoring and sleep apnea—disorders that further worsen sleep fragmentation and poor sleep quality. The subjective perception of a good night’s sleep, often reported after alcohol consumption, does not match objective polysomnography data, which show less restorative sleep and greater fatigue the following day.
It is important to note that the effects of alcohol vary among individuals, with women potentially being more sensitive due to metabolic and hormonal differences. Using alcohol as a sleep aid is therefore a counterproductive strategy that impairs cognitive and emotional functions as well as physical performance in daily life.
In conclusion, evidence from the systematic review reinforces that alcohol, although it may facilitate sleep onset, compromises overall sleep quality—especially by reducing REM sleep, which is crucial for cognitive and emotional processes. Other complementary studies confirm these findings²,³, showing that regular alcohol consumption is associated with greater sleep fragmentation and poorer daytime performance, including fatigue, impaired attention, and mood disturbances. Furthermore, research indicates that the negative impact of alcohol on sleep may be even more pronounced in vulnerable populations, such as older adults and individuals with pre-existing sleep disorders. Therefore, the recommendation is to avoid using alcohol as a sleep aid and to focus on practices that promote natural and restorative sleep, thereby ensuring better health and quality of life.
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