- People tend to experience different levels of alertness from day to day, while also differing from other people in their average daily alertness levels.
- A recent longitudinal study suggests that the previous night’s sleep profile, physical activity during the previous day, and the nutritional composition of breakfast were all related to daily variation in a person’s morning alertness levels.
- The study also found that non-genetic factors, including mood, sleep quality, age and frequency of daily food intake, predicted differences in morning alertness between individuals.
- The study reported a modest effect of genetic factors on daily alertness, suggesting that interventions to modify non-genetic factors could help improve levels of daily alertness.
Impaired alertness immediately after waking and throughout the day can negatively affect cognitive and motor performance and increase safety risks.
A recent study published in nature communications suggests that several modifiable lifestyle factors, such as sleep quality and duration, may have a greater impact on morning alertness levels than genetic factors.
These results suggest that interventions at the individual and societal level targeting these non-genetic factors could help alleviate the negative consequences associated with impaired alertness.
the inertia of sleep refers to the phase of deterioration in alertness and performance that occurs between sleep and wakefulness, and it can last minutes to several hours after waking up.
Although it is a common phenomenon, it can have a profound impact on people’s productivity and safety.
Specifically, sleep inertia can affect the safety of workers in hazardous occupations or affect the decision-making of emergency services personnel, including health care workers and firefighters, which can influence the safety of others.
Likewise, decreased alertness throughout the day due to inadequate sleep is associated with lower productivity and increased risk of traffic accidents.
However, there is limited scientific evidence on the factors that influence alertness levels after awakening.
In the present study, the researchers evaluated factors associated with daily variation in morning alertness in the same individual.
They also examined the role of genetic versus non-genetic factors in influencing differences in average morning alert levels between individuals.
The researchers first examined the impact of four prespecifiedfactors on the daily variation in alertness observed within the same individual.
They assessed the impact of the previous night’s sleep profile, previous day’s physical activity, breakfast nutritional composition, and post-breakfast blood sugar levels on morning alertness. Participants recorded their dietary intake and alertness in the ZOE study app, throughout the study. The study was funded by ZOE Ltd.
To examine the impact of these factors, the researchers used data collected over a 2-week period from 833 people ages 18 to 65. Participants had to wear a wristwatch accelerometer throughout the study period to facilitate data collection on their sleep profile and physical activity levels.
For the morning alertness assessment, participants recorded alertness levels in an app on a scale of 0 to 100. They reported their first alertness rating at the start of breakfast and then intermittently over the next 3 hours.
Based on each participant’s baseline sleep profile, the researchers found an association between sleep duration and sleep timing with morning alertness levels.
Specifically, when a participant slept in more than usual or woke up later than usual, they were more likely to show higher levels of alertness the next morning.
Higher levels of physical activity during the previous day were also associated with greater morning alertness.
Only physical activity levels during the 10 busiest hours of the previous day were positively correlated with morning alertness levels.
In contrast, physical activity at night was associated with lower morning alertness.
The researchers then examined the impact of the macronutrient composition of breakfast on morning alertness. They provided standardized calorie-equivalent breakfasts of various nutritional compositions, including high carbohydratehigh-protein and high-fiber meals for each participant, which were consumed on different days.
The researchers compared the participants’ alertness levels after consumption of each of these meals with that of a reference meal that provided moderate levels of carbohydrates and protein.
Among the different standardized meals provided to the participants, consumption of a high-carbohydrate breakfast was associated with higher levels of morning alertness than the reference meal.
In contrast, the high-protein breakfast was associated with lower alertness levels than the reference meal.
The researchers also examined how changes in blood glucose (sugar) levels after breakfast consumption influenced morning alertness levels.
Regardless of the composition of the breakfast, lower blood glycemic loada measure of the impact of food intake on blood glucose levels, after breakfast was associated with increased morning alertness.
In particular, these four factors influenced morning alert levels independently of each other.
jeff kahnCEO and co-founder of subscription sleep and energy tracking app Rise Science, who was not involved in this study, commented on the findings, saying today’s medical news that:
“The study helps demonstrate that positive health and wellness outcomes—in this case, increased alertness—can be achieved through a variety of levers. The four contributions of independent impact that they cite (longer than normal sleep duration, previous daytime exercise, breakfast composition rich in carbohydrates but still diverse in macronutrients, and a lower glycemic response in the hours after breakfast consumption) are tools discrete ones in our performance toolbox that we can use and benefit from, even if we can’t achieve all four every time.”
While these factors explained daily differences in morning alertness within the same individual, the authors were also interested in factors that might explain why certain participants had higher average alertness levels than others.
In other words, the researchers were interested in genetic and/or lifestyle factors that might influence an individual’s average or characteristic daytime alertness levels.
The researchers found that positive mood, older age, fewer meals during the day, and better sleep quality were predictors of an individual’s average daily alertness levels.
The present study consisted of genetically unrelated twins and adults. This allowed the researchers to examine the extent to which genetic factors might influence daily alertness levels in the twins.
The researchers found that genetic factors had a small impact on an individual’s alertness levels, suggesting a more significant impact from lifestyle factors that are amenable to modification.
Dr Andrew McHilla sleep researcher at Oregon Health and Science University, who was not involved in this study, commented that “[u]Unique to this current study is the wide range of predictors that were collected (sleep, diet, and activity) and the ability to separate these behaviors versus genetic influences by using the twin study.”
“Using this type of analysis allows for a more accurate assessment of potentially modifiable behaviors to improve next-day alertness. This is not only exciting for potential individual and societal targets for improving safety and health, but also for the research community, as it provides more testable hypotheses for future examination to identify what exact mechanisms are causing these observed changes in health status. alert,” he added.
The researchers acknowledged that their study had some limitations. For example, the morning alert levels in the study were based on self-reports and could be susceptible to bias.
The study also did not account for differences in light exposure in the morning, a factor known to significantly improve alertness.
The researchers further noted that all of the standardized breakfasts consisted of carbohydrates, protein, and fat and only varied in the levels of these macronutrients.
They cautioned that these results should not be taken literally and lead to the adoption of carbohydrate-only meals for breakfast.
