The Busier You Are, the More Effective It Is: Health Habits Are Determined by "Order" Rather Than "Willpower"

"Exercise or Sleep Early?" The Research-Backed "Priority" for Indecisive Nights

Work, house chores, childcare, commuting. There's a mountain of things to do, yet the time available for body maintenance is limited. This leads everyone to face that dilemma at least once.

"Should I exercise today? Or should I get some sleep?"

A recent study introduced by Germany's n-tv has provided a clear direction for this "dilemma." To cut to the chase, if you can only choose one, prioritize sleep. This approach tends to increase the activity level (steps) the following day, while the effect of "I walked, so I'll sleep well tonight" might not be as significant as expected. Ntv

Examining "Sleep → Exercise" with 70,000 People and 28 Million Days of Life Logs

The reason this study is compelling lies in its scale and "realism." The research team used records obtained from sleep sensors placed under beds and wrist fitness trackers, tracking the relationship between sleep and physical activity (steps) on a daily basis from a massive dataset of 70,963 people and approximately 28 million days. Ntv

The first reality check is that few people live ideally.
Habitually achieving the recommended **"7-9 hours of sleep" and "over 8,000 steps a day" was possible for only 12.9% of the total. Moreover, 16.5%** fell into the high-risk category of having less than 7 hours of sleep and fewer than 5,000 steps. Nature

In other words, many people lack either "sleep or exercise (or both)." Rather than a lack of effort, the data suggests that the guidelines might be "designed to be difficult to achieve simultaneously." Nature

The Crux of the Study: "Quality of Sleep" Influences the Next Day's Steps

The core of the study is the "direction" between sleep and exercise. Generally, there's a strong perception that "exercise helps you sleep," but this analysis highlighted the opposite.

• The higher the sleep quality (especially sleep efficiency), the more steps taken the next day
  . Specifically, comparing those with low sleep efficiency (25th percentile) to those with high sleep efficiency (75th percentile) showed a tendency for an increase of **+282 steps/day** the following day. Nature

• On the other hand, the previous day's steps have a minimal effect on significantly improving that night's sleep (summarized as "sleep is hardly affected by steps"). Nature

Another result likely to spark debate is the analysis showing that **"about 6 hours of sleep corresponds to the maximum steps the next day"** (e.g., +339 steps compared to 8 hours of sleep). However, the researchers caution that factors such as longer waking hours leading to more steps can mix in, and adjusting for waking time reduces the effect. Thus, rather than recommending "short sleep," it's safer to interpret this as data showing that the relationship between sleep and activity is not a simple straight line. Nature

The Practical Reason for the Strategy of "Prioritizing Sleep"

Why does sleep tend to come "first"? According to the n-tv article, factors such as energy, motivation, and ease of movement are cited as reasons why high-quality sleep supports the next day's activities. Ntv

Conversely, "exercise → sleep" is influenced by many factors such as the intensity and timing of exercise, accumulated fatigue, stress, alcohol consumption, and light before bedtime, leading to significant variability in effectiveness. This suggests that, on average, the effect is less noticeable.

Additionally, the study includes important "caveats." It points out that wearable users may have biases in health awareness and socioeconomic status, and that sleep trackers might overestimate sleep duration, suggesting that the reality might be even harsher. Ntv

Connecting the "Ideal" Guidelines with the "Reality" of Life

So, is it okay to put off exercise? Of course not. Exercise is broadly involved in cardiovascular disease risk, metabolism, musculoskeletal health, and mental health, and the WHO recommends adults engage in at least 150 minutes of moderate-intensity activity (or 75 minutes of high-intensity) per week. Ntv

What this study suggests is a shift in thinking about priorities.

• You can't always keep everything

• So start by building a "stable foundation"

• Once the foundation is set, the next actions (activity levels) are easier to increase

This approach is particularly effective for busy people. Exercise tends to be added with "willpower," but sleep is the first to be cut unless it's "secured first." If there's only one thing you can do for yourself today, sleep. That increases the likelihood of walking tomorrow—the study shows such a realistic winning strategy. Ntv

Reactions on Social Media (Typical "Reaction Patterns" When This Topic Spreads)

This topic almost certainly fuels discussions on social media. "Exercise vs. Sleep" easily ties to everyday experiences and can be asserted in short phrases. Recently, platforms like TikTok, Instagram, and YouTube have seen a trend of prioritizing sleep for "optimization," "Sleepmaxxing", with numerous sleep hacks and routines being shared. RND.de

On social media, the following reactions typically emerge.

1. Empathy: "When in doubt, sleep. Totally get it."
   "When I'm sleep-deprived, exercise is out of the question," "On days when I've had enough sleep, I can move naturally"—these are "experience-based" agreements that align well with the study's "sleep → steps" direction. Nature

2. Counterargument: "But I sleep like a log on days I exercise!"
   Those with experience in running or strength training strongly believe in "exercise → sleep." The study acknowledges the complexity of exercise's effects, suggesting that on average, the impact might appear small. Ntv

3. Misinterpretation & Controversy: "Does this mean 6 hours of sleep is the best?"
   It tends to be interpreted as "short sleep is fine." In reality, there are caveats such as the effect weakening with adjustments for waking time, making it risky to consume as praise for short sleep. Nature

4. Wearable Discussion: "Ultimately, the problem of being swayed by numbers"
   With the expansion of Sleepmaxxing, there's a tendency to focus excessively on scores and metrics. Overseas, issues like "orthosomnia" (obsession with sleep metrics that disrupts sleep) are also being introduced. Axios
   n-tv also warns that "sleep hacks" from SNS can include dangerous or poorly substantiated ones. Ntv

In summary, on social media, there's a tailwind for "valuing sleep" and a backlash against "over-optimization of numbers and hacks" happening simultaneously. The key to effectively using this study is not to use sleep as an excuse or to turn it into a competition, but to incorporate it as a "priority design."