The research consistently points in one direction: alcohol harms sleep quality, particularly restorative deep sleep and REM sleep. This is likely causal, although the evidence is based on reviews rather than large randomised trials. In practical terms, the best step is to avoid drinking alcohol close to bedtime; effective dietary supplements as a countermeasure have not yet been demonstrated.
Alcohol may appear to make falling asleep easier at first, but that benefit is deceptive. A large amount of alcohol just before bedtime acts as a sedative: you fall asleep faster and sleep seems deeper in the first part of the night. However, once your body has broken down the alcohol, that effect reverses entirely. In the second half of the night, sleep becomes disrupted and poor in quality. On balance, alcohol therefore harms sleep architecture, even if it does not feel that way in the moment.
In people who structurally drink too much or who are alcohol-dependent, the damage goes further. There is chronically less deep sleep (the restorative slow-wave sleep) and a disrupted REM sleep pattern. These are precisely the sleep stages that matter for physical and mental recovery. What is concerning is that these disruptions persist for a long time, even well into periods of abstinence, and may contribute to relapse into drinking behaviour.
There is also a reverse dynamic at play. Poor sleep quality can itself lead someone to use more alcohol (and caffeine), presumably as self-medication. This can become a vicious cycle: alcohol disrupts sleep, sleeping worse increases the desire for alcohol, and so on. This relationship is for now associative rather than a proven cause-and-effect relationship, but the pattern is recognisable and relevant.
The most direct way to address alcohol-related sleep problems is of course to reduce alcohol consumption, or at the very least to stop drinking close to bedtime. For those who want to support sleep quality through diet, there are cautious indications. Nutrients such as tryptophan (found in milk and eggs), omega-3 fatty acids (oily fish), vitamins B6, B12 and D, and minerals such as magnesium and zinc are associated with better sleep in the scientific literature. However, this concerns observational research, not evidence that supplements or specific foods resolve sleep problems caused by alcohol.
Glycine, an amino acid that occurs naturally in the body, is described in a narrative review as potentially beneficial for sleep quality. However, the evidence for this is thin and insufficient to base concrete recommendations on. Glycine supplements are therefore not a proven remedy for sleep disruption caused by alcohol.
All claims are based on one primary review on alcohol and sleep (PMID 25307588), supplemented by two nutritional studies (PMID 40728459, PMID 34610163) and one narrative review on glycine (PMID 28337245). No RCTs or meta-analyses are available on interventions that actively counteract alcohol-related sleep disruption.