You wake up at 6:30 feeling like a wreck, while your coworker—who went to bed at 2 a.m.—strolls in fresh as a daisy and solves a problem in an hour that you’ve been wrestling with all morning. Sound familiar? We used to call this laziness or a lack of discipline. But a massive study involving over 26,000 adults, led by researchers at Imperial College London, suggests something else entirely: it might just be biology.

Researchers rigorously tested memory, reaction speed, reasoning, and complex thinking capabilities. The result was clear and unambiguous: “evening types” (people who naturally fall asleep late and wake up late) outperformed “morning types” on cognitive measures. The difference wasn’t tiny—it was statistically significant and impossible to explain by mere chance.

In other words, when a morning lark is already getting a bit foggy at 9 a.m., a night owl is just hitting their stride. Their brain works faster, sharper, and more creatively.

Why Does This Happen? A Simple Psychological Explanation

We all possess an internal clock known as the circadian rhythm. It controls not just sleep, but body temperature, hormone levels, metabolism, and even when different specific parts of the brain are most active.

The hormonal schedule differs dramatically between chronotypes:

• Morning people: They experience their cortisol (wakefulness hormone) peak between 6:00–8:00 a.m. and start producing melatonin (sleep hormone) around 9:00–10:00 p.m.
• Night owls: Their cortisol surge is shifted to 10:00 a.m.–noon, and melatonin often doesn't kick in until close to midnight or even 1:00 a.m.

Here’s the really interesting part: brain imaging studies show that in evening types, the prefrontal cortex—the area responsible for planning, flexible thinking, creativity, and impulse control—lights up most strongly in the late afternoon and evening. Their brain literally “turns on” later, but when it does, it runs at full power.

Think of it like car engines: a morning person is a diesel—quick to warm up, steady, but often with a limited top speed. A night owl is a turbocharged petrol engine—it takes longer to get going, but once it’s hot, it leaves the diesel in the dust.

Compelling Scientific Evidence

The science backing this is robust. In the Imperial College data analysis, evening types scored significantly higher on working memory tests and reacted faster on speed-of-processing tasks compared to their early-rising counterparts.

Furthermore, a seminal study from the University of Liège (Belgium) found that forcing a night owl to wake up at 7 a.m. creates a massive cognitive deficit. However, the reverse is even more telling: force a morning person to stay up late, and their cognitive performance drops, but nature clearly didn’t deal the cards evenly. Night owls can often maintain attention longer into their waking day than morning larks can.

But Doesn’t Everyone Say Waking Up Early Is Healthy?

Yes, they do. And they’re partly right. Early rising fits school, university, and most corporate office schedules perfectly. Plus, you get sunlight and social approval. But here is the critical distinction: It is only healthy if it matches your genetics.

If you are genetically a night owl (and that is roughly 15–20% of the population), trying to “retrain” yourself into a morning person leads to a condition known as social jetlag. This results in chronic sleep deprivation, accumulated sleep debt, elevated cortisol, and higher rates of anxiety, depression, and even an increased risk of obesity and type 2 diabetes. That isn’t just an opinion; that is a fact backed by dozens of longitudinal studies.

So yes, you can heroically drag yourself out of bed at six—but you’re paying for it with your long-term health and mental sharpness.

So What Should You Actually Do?

Exactly what the authors of the study emphasize: the single most important thing is not “early or late,” but consistency and getting enough sleep duration.

If you are a night owl:

• Try to go to bed and wake up at roughly the same time (±1 hour).
• Get your 7–9 hours even if that means sleeping from 2 a.m. to 10 a.m.
• Save hard, creative, or learning-heavy tasks for after 6:00–7:00 p.m.—that is when you are at your physiological best.
• In the morning, give yourself time to warm up: coffee, bright light, and light movement are essential.

If you’re a morning person—congratulations, society is built for you. Just don’t start staying up until 2 a.m. “because everyone else does.”

The Conclusion Night Owls Have Been Waiting For

You’re not lazy. You’re not “undisciplined.” You are wired differently. And when you get your full 8 hours on your own schedule, your brain can produce results many morning people will never reach, even on their best day.

So the next time someone says, “What, you sleep till noon?”, you can calmly reply: “Yep, because my brain is just warming up so it can lap yours on every cognitive test later.”

And that won’t be bragging.

That will be science.

References

• West, R., et al. (2024). Sleep duration, chronotype, health and lifestyle factors affect cognition: a UK Biobank cross-sectional study. BMJ Public Health. (This is the "Imperial College" study analyzing data from over 26,000 people, confirming evening types have superior cognitive scores).
• Schmidt, C., et al. (2009). Homeostatic sleep pressure and responses to sustained attention in the suprachiasmatic area. Science. (The "University of Liège" study demonstrating that night owls can maintain higher brain activation in the prefrontal cortex for longer periods than morning types).
• Roenneberg, T., et al. (2012). Social Jetlag and Obesity. Current Biology. (Evidence regarding the health risks of misalignment between internal clock and social schedules).