We often think of sleep as “downtime,” but research shows it’s one of the most powerful regulators of appetite, metabolism, and long-term health. In fact, a fascinating study from Columbia University found that people who slept just 4 hours per night ate an extra 300 calories per day compared to when they slept for 9 hours.
Now, 300 calories might not sound like much—but over time, it really adds up. That’s around 2 kg of body fat in just six months, or 20 kg over 5 years if the habit continues unchecked. And here’s the kicker: most of those extra calories came from foods high in saturated fat, raising not only weight gain risk but also cardiovascular risks.
We often think of sleep as “downtime,” but research shows it’s one of the most powerful regulators of appetite, metabolism, and long-term health. In fact, a fascinating study from Columbia University found that people who slept just 4 hours per night ate an extra 300 calories per day compared to when they slept for 9 hours.
How Sleep Loss Affects Eating
When you’re sleep-deprived, your body’s hunger hormones shift out of balance. Levels of ghrelin (the “I’m hungry” hormone) increase, while leptin (the “I’m full” hormone) decreases. That means your brain keeps signalling for food even when you don’t actually need it . In the Columbia study, women were more affected than men—eating an extra 329 calories per day, compared to 263 extra calories for men. Over years, this difference can have a profound impact on body composition and health outcomes. The researchers followed 26 healthy men and women, tracking their eating behaviours across six nights of short sleep (4 hours) versus six nights of long sleep (9 hours). The conclusion? Chronic short sleep predisposes people to weight gain, obesity, and higher cardiovascular risk.
What This Means for Shift Workers
For those working irregular hours or night shifts, this research hits especially close to home. Shift workers often struggle with disrupted sleep patterns—and the data shows they’re at greater risk for obesity, heart disease, and diabetes . But there are strategies that can help:
- Prioritise Sleep: Aim for at least 7 hours per day—not just the bare minimum. Use blackout curtains, eye masks, or white noise to improve sleep quality.
- Pre-Plan Meals: Don’t leave food choices to late-night cravings. Pack balanced meals and snacks ahead of time.
- Practice Conscious Eating: Ask yourself: Am I really hungry, or am I bored, stressed, or tired? If it’s the latter, try another coping strategy like taking a short walk, stretching, or drinking water.
- Keep a Routine: Even on days off, try to maintain a consistent sleep-wake schedule to stabilise appetite hormones.
The Bigger Picture
Poor sleep doesn’t just impact your waistline—it influences your metabolism, mood, immune system, and heart health. Building better sleep habits may be just as important as diet and exercise when it comes to living longer, stronger, and healthier. Think of sleep as your body’s reset button. Without enough of it, even the best eating and exercise habits won’t be as effective. The Bottom Line If you’re trying to manage your weight, improve your energy, or reduce disease risk, don’t overlook sleep. Protecting your rest is protecting your health. So tonight—switch off the screens, dim the lights, and give your body the rest it deserves. Your future self will thank you.
References
- St-Onge MP, et al. Short sleep duration increases energy intakes but does not change energy expenditure in normal-weight individuals. Am J Clin Nutr. 2011.
- Spiegel K, Tasali E, et al. Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite.
- Ann Intern Med. 2004. American Heart Association. Short sleep duration and its impact on health. AHA News Release.
- Australian Institute of Health and Welfare. Health impacts of shift work. AIHW,
