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.

References

1. Gardiner C, Weakley J, Burke LM, Roach GD, Sargent C, Maniar N, Huynh M, Miller DJ, Townshend A, Halson SL. The effect of alcohol on subsequent sleep in healthy adults: A systematic review and meta-analysis. Sleep Med Rev. 2025;80:10203.
2. Kim HJ, Lee SY, Park JH, Kim SH, Choi J, Lee HW. Enhanced alcohol metabolism and sleep quality with continuous positive airway pressure in patients with obstructive sleep apnea. Sci Rep. 2025;15(1):17345.​
3. Pabon E, Caldwell JA, Swamy RN, Bailey SJ, Wilkinson M. Effects of alcohol on sleep and nocturnal heart rate: behavioral and physiological outcomes. Alcohol Clin Exp Res. 2022;46(3):408-416.