- Study utilized data from over 4,000 men and women in real-world conditions
- Heart rate variability (HRV) offers objective insight into restorative power of sleep
- Even a single drink has a negative impact on sleep quality
- Similar results for men and women and for physically active vs sedentary people.
- Younger people experience an even greater reduction in sleep quality from alcohol.
A glass of wine may be a popular way to relax in the evening, but does it also help you sleep? New research sheds light on this question by connecting the dots between alcohol consumption and its impact on the restorative quality of sleep.
The new study from Finland is unique in that it utilized data from over 4000 men and women recorded in the real-world conditions of daily life. Notably, even a single drink had a demonstrably negative impact on the restorative quality of sleep.
Sleep needs vary from person to person, but also from day to day. While some individuals tend to need more, others require less. A mounting body of evidence shows that daily routines, activities, and consumption patterns play role in sleep quality, making it important to investigate the relationship between what a person does and how well they sleep.
“It’s hard to overstate the importance of sleep, in terms of both quality and quantity,” says Tero Myllymäki, Firstbeat’s head of physiology and study contributor. “While we may not always be able to add hours to our sleep time, with insight into how our behaviors influence the restorative quality of our sleep we can learn to sleep more efficiently. A small change, as long as it’s the right one, can have a big impact.”
So How Does Alcohol Impact Sleep Quality?
According to the study, consuming alcohol has a universally negative impact on the restorative quality of sleep. The degree of impact varies based on the quantity of alcohol consumed with even a single unit of alcohol producing a discernible reduction in restorative sleep quality.
When it comes to recognizing the effects of alcohol consumption, the larger the dose, the easier the effects are to spot. However, just because you didn’t binge or wake up the next morning with a hangover to shake off doesn’t mean you snuck one over on your body.
Findings were similar for men and women, and for physically active and sedentary participants. The reduction of sleep quality following alcohol consumption was larger for younger people than for older, and larger for individuals with a lower normal heart rate during sleep than for those with a higher sleeping heart rate.
“When you’re physically active, or younger, it’s easy, natural even, to feel like you’re invincible,” says Myllymäki. “However, the evidence shows that despite being young and active you’re still susceptible to the negative effects of alcohol on recovery when you are asleep.”
This is particularly noteworthy in light of studies that indicate being more physically active relates to increased alcohol consumption among non-alcoholics.
Looking specifically at the first three hours of sleep after alcohol consumption, physiological recovery was reduced on average by 9.3% with low alcohol intake, 24.0% with moderate alcohol intake, and by 39.2% for high alcohol intake.
For the purpose of the study, low, moderate and high alcohol consumption were assessed in terms of grams of alcohol relative to body weight. Although for the average person, these categories equate to roughly 1-2 drinks, 2-6 drinks, and more than 6 drinks respectively.
Objectively Measuring Sleep Quality
To examine the restorative quality of sleep, the study utilized heart rate variability (HRV) as a window through which to examine activity occurring within the autonomic nervous system (ANS). Interpreting the HRV phenomenon gave the researchers access to the presence and magnitude of stress and recovery reactions in the body via activation of the sympathetic (fight-or-flight) and parasympathetic (rest-and-digest) branches of the ANS.
Firstbeat Research Database
Data used in the study came from the Firstbeat research database, which included total of 111,025 days of HRV data from 42,086 individuals. Each of these individuals participated in the Firstbeat Lifestyle Assessment, which typically utilizes a 72-hr recording of HRV data along with other tools to explore the relationship between stress, recovery, physical activity and well-being. HRV data was recorded using the Firstbeat’s Bodyguard 2 professional-grade HRV recording device in real-world conditions of daily life.
To investigate the relationship between alcohol and sleep quality, data from 4,098 individuals was utilized and selected based on certain criteria. Participants were assessed between 2007 and 2015, were between 18 and 65 years old at the time of assessment, and included sleep recordings from at least two nights, one with alcohol consumption and the other without.
The Firstbeat research database is used to investigate topics of sleep, stress, recovery, and physical activity. As of 2018, the database has grown to include over 350,000 days of assessment data from approximately 120,000 individuals.
Acute Effect of Alcohol Intake on Cardiovascular Autonomic Regulation During the First Hours of Sleep in a Large Real-World Sample of Finnish Employees: Observational Study
Full text available: http://mental.jmir.org/2018/1/e23/
Contributors to the Study included: Julia Pietilä (1), MSc; Elina Helander (1), PhD; Ilkka Korhonen (1,2), PhD; Tero Myllymäki (2,3), MSc; Urho M Kujala (4), MD, PhD; Harri Lindholm (5,6) MD, PhD.
- Faculty of Biomedical Sciences and Engineering, BioMediTech Institute, Tampere University of Technology, Tampere, Finland
- Firstbeat Technologies, Jyväskylä, Finland
- Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
- Finnish Institute of Occupational Health, Helsinki, Finland
- Nokia Technologies, Espoo, Finland