Key Takeaways

• Late-night habits, like staying up late or nighttime eating, can accelerate cellular aging, impair metabolic function, and increase the risk of cognitive decline.
• Circadian rhythm disruption affects hormones such as cortisol and melatonin, resulting in blood sugar imbalances, inflammation, and poor sleep quality.
• Establishing a regular sleep schedule, limiting screen time, and avoiding late-night meals can support healthy aging and improve long-term metabolic and cognitive health.

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If you’re like many, it can sometimes feel like there isn’t enough time in the day! With busy schedules and endless to-do lists, it’s easy to fall into habits like staying up late to squeeze in extra work (or simply time for yourself), eating meals right before bed, or pushing through fatigue to keep going. While these routines might seem harmless (or even necessary), they can take a toll on your body over time.

What many people don’t realize is that the timing of our daily routines (when we eat, sleep, and move) can have a profound influence on our overall health. Staying up late, eating meals close to bedtime, and experiencing disrupted sleep can have profound effects on aging and metabolic health. By understanding how these patterns affect us (often without us even realizing it), we can begin to make smarter, more intentional choices to support long-term health and longevity.

The Impact of Nighttime Wakefulness on Aging

Did you know your body runs on a clock, even if you have no idea what time it is? This clock is known as your circadian rhythm, and we all have one that is as unique to us as our fingerprints. The circadian rhythm regulates the sleep-wake cycle, as well as other bodily functions that occur throughout the day. Think of it as your body’s internal clock that knows when to make you tired or alert, hungry or satiated, and even whether your body should be hot or cold. On average, in the absence of time cues, one cycle lasts about 24.2 hours, but exposure to external cues like sunlight, regimented work hours, and alarm clocks can disrupt this cycle.¹

Interfering with this cycle (such as staying up late) can have a negative impact on your health. Remaining awake during hours typically reserved for sleep can interfere with the body’s natural repair processes. The result? Even if your chronological age doesn’t change, you can get older at a cellular level.

One way this occurs is through a process known as telomere shortening. Telomeres are protective caps on chromosomes (structures in cells that contain DNA). As cells divide, telomeres shorten and are therefore viewed as a marker of cellular aging and disease. While some animal studies show a link between telomere length and longevity, others have not. 

Researchers studied the telomere length of mice, rats, and naked mole rats (which have a longer lifespan) and found a link with longevity only in the mice and rats.² The authors concluded that telomere length may predict lifespan in short-lived animals but may not be a strong predictor in longer-lived animals, including humans. Further research in animals suggests that the rate of telomere shortening may matter more than the length of the telomeres themselves.³

Chronic late-night wakefulness has been linked to accelerated telomere shortening. One study of nearly 3,000 Dutch adults found that individuals classified as “night owls” have shorter telomeres, even if they get sufficient sleep each night.⁴ This suggests that it is not a lack of sleep that causes cellular aging, but rather sleep patterns that lead to disruption of the circadian rhythm.

Disrupted sleep patterns can also lead to hormonal imbalances that may be related to aging. The body’s internal clock regulates the release of various hormones, which control a wide range of bodily processes. Two of these hormones are cortisol and melatonin, both of which play a role in aging.

You probably think of melatonin as the supplement you take when you have trouble sleeping. Melatonin is naturally produced by the body and released two to three hours before bedtime. As levels of melatonin start to fall, it signals that it’s time to sleep. Beyond its role in sleep, melatonin may also function as an antioxidant to help repair cells damaged by oxidative stress.⁵ Because of this, melatonin may also protect against age-related cognitive decline and the development of neurodegenerative diseases, like Alzheimer’s disease.⁶

Cortisol is the body’s stress hormone. In caveman times, stress typically meant there was a war or a woolly mammoth attack; all times when it would be crucial to have enough energy to help you fight or run away. Modern-day stress may be more sedentary, but it still elicits the same hormonal response: higher stress leads to the release of cortisol, which triggers the liver to release stored glucose, increasing blood glucose levels.

During sleep, cortisol is naturally lower. Sleep deprivation interrupts this circadian rhythm, contributing to elevated blood sugar and a higher risk of insulin resistance and type 2 diabetes. Sleep deprivation and disrupted sleep patterns are also associated with increased levels of inflammatory proteins, such as TNF-α and C-reactive protein, which contribute to cellular aging.⁷

Nighttime Eating and Metabolic Disruption

If you’re staying up late, you may find that you’re hungry. While your body needs energy, consuming food late at night can have adverse effects on metabolism and increase the risk of chronic diseases.

Insulin levels naturally decrease at night. Without a strong insulin response, consuming food late at night may lead to glucose spikes. As described in the previous section, higher cortisol levels resulting from sleep disruption and circadian misalignment can also contribute to increased blood sugar, as the liver releases stored glucose for energy. Over time, this increase in glucose without an appropriate insulin response can contribute to the development of insulin resistance, diabetes, and metabolic syndrome.

Insulin resistance can also contribute to weight gain as excess sugar in the blood gets stored as fat. Nighttime eating specifically has been linked to weight gain. Here are some other ways that nighttime eating can contribute to weight gain:

• Nighttime eating typically refers to additional meals or snacks that you might not have consumed if you were asleep. This is a simple calculation of calories in and calories out, with the balance tipping higher on the side of calories in.
• Late-night food choices are often less nutritious. High-carbohydrate foods like candy and ice cream are highly palatable but not very filling, making it easy to overeat, especially when you are already stressed while trying to complete important work tasks.
• Eating late at night makes you hungrier the next day. A study of 16 people with overweight or obesity found that late eating was linked to lower levels of the hormone leptin, which increases satiety, for 24 hours after.⁸ With less leptin, you feel less satisfied, resulting in cravings for highly palatable foods and increased food intake.
• Late-night eating is associated with a decreased metabolic rate and lower energy expenditure (calorie burn) compared to daytime eating. This was tested in a sample of mice. Researchers fed one group of mice during their active period and another group during their inactive period and found that the mice who ate when they should have been sleeping had higher body fat.

Sleep Deprivation and Cognitive Decline

Insufficient sleep not only affects physical health but also has implications for cognitive function. A meta-analysis of almost 70,000 participants found that those with sleep problems (who therefore were not sleeping enough) had a 50% increased risk of developing Alzheimer’s disease (AD) and were almost four times as likely to develop preclinical AD.⁹ In fact, the authors estimate that about 15% of AD may be attributed to sleep problems. Beyond Alzheimer’s, sleep deprivation impacts our ability to perform cognitive tasks and impairs attention, working memory, emotions, and learning.^10,11

What causes these effects? One possible reason involves the impact of sleep deprivation on the body’s glymphatic system.¹² The glymphatic system is a newly discovered waste removal system in the brain that is most active during sleep. Shorter sleep duration limits the body’s ability to clear waste from the brain. As a result, waste products accumulate, contributing to cognitive decline. Sleep deprivation is also associated with a reduction in certain proteins that are involved in different aspects of cognition, such as calcium calmodulin-dependent protein kinase II (CaMK-II) and cAMP Response Element Binding Protein (CREB).¹²

Even with adequate sleep, a recent study conducted in the Netherlands found a link between wake-sleep patterns and cognitive decline.¹³ The study is based on something called a “chronotype”, which refers to the body’s natural tendency toward a specific wake-sleep pattern (think of “early birds” compared with “night owls”). Night owls showed faster mental decline than early birds. 

The good news? Nearly one-fifth of the risk of cognitive decline can be attributed to unhealthy habits that are more common among night owls, such as smoking. Interestingly, researchers also found a stronger effect of chronotype on cognitive status among people with higher education levels. More highly educated night owls were most likely to experience cognitive decline. Researchers suspect this is because these night owls are forced to adapt their sleep habits to comply with rigid work hours and early start times, resulting in less sleep than their bodies (and brains) need.

Strategies to Mitigate Late-Night Health Risks

Whether you’re a night owl or an early bird without enough hours in the day, staying up late can have a negative effect on your health. But don’t despair! Implementing certain lifestyle changes and sleep habits can help counteract the negative effects of late-night habits. Follow these strategies to improve your sleep quality and lower your risk of poor health outcomes:

• Establish a consistent sleep schedule: Going to bed and waking up around the same time every day (yes, even on weekends) helps reinforce your circadian rhythm and improve sleep quality. Set bedtime and wake-up times and stick to them. Creating a bedtime routine can help you wind down.
• Avoid late-night eating: It should be clear by now that late-night eating is detrimental to health and leads to poor sleep. Focus on eating balanced meals throughout the day. If you are forced to stay up late to finish a task and feel hungry, opt for a balanced snack that contains both fiber and protein. (By the way, casein, a protein found in milk, has been found in some studies to improve sleep quality¹⁴ - if you’re hungry late at night, try a small bowl of yogurt with some fruit.)
• Limit exposure to screens before bed: Blue light emitted by screens can prevent melatonin from being released, making it harder to fall asleep.¹⁵ Screen time before bed can also make it hard to shut off your brain, disrupting sleep. Set boundaries around screentime. Swap TV time for a good book and consider leaving your phone outside of the bedroom.
• Engage in relaxation techniques: Deep breathing, guided imagery, and meditation may help you get better sleep. Not into mindfulness? Sleepy drinks containing magnesium or tart cherry juice may also help you fall asleep and stay asleep.¹⁶

While sleep quality matters, it is just one piece of the puzzle. Other risk factors, including physical activity, overall healthy eating patterns, and use of tobacco or alcohol, also contribute to long-term health and wellness.

The Bottom Line

Late-night behaviors, such as staying up late and eating close to bedtime, can accelerate aging and disrupt metabolic health. By understanding these risks and adopting healthier habits, you can enhance your overall well-being and lower the likelihood of developing chronic health issues. If you struggle with sleep, talk with a healthcare provider for personalized guidance.

Learn More With Signos’ Expert Advice

Blood sugar health seriously affects how you feel and how well your body functions. That’s why it’s so important to understand how different things affect your blood sugar levels. 

A CGM empowers you to improve your health by tracking your diet, exercise, sleep habits, and blood sugar levels. Knowledge is power, and a CGM can provide you with specific information about how your habits impact your health. 

Signos has a team of health experts who compile evidence-based nutrition information to help you improve your health and wellness. Check out the resources here.