Jet Lag and Night Shifts: What They’re Doing to Your Blood Sugar (and How to Fix It)

Key Takeaways

• Jet lag and night shifts can disrupt your body’s internal clock, disrupting hormones such as insulin and cortisol that regulate blood sugar and energy levels. 
• Circadian misalignment increases the risk of insulin resistance, blood sugar spikes, and type 2 diabetes, even in otherwise healthy individuals. 
• You can protect your metabolic health with strategies such as regular meal timing, quality sleep, exposure to natural light, and mindful eating, whether you’re traveling or working overnight shifts.

 {{mid-cta}}

If you think of your circadian system as your body’s natural timekeeper, when you travel across time zones or work through the night, that rhythm gets thrown off. Suddenly, hormones are out of sync, and your blood sugar can hit some surprising highs and lows. 

Jet lag and night shift work are more common than ever in our world, but they might come with a hidden cost of disrupting your metabolic health. Research shows that when your sleep and eating patterns fall out of rhythm, your body has a harder time processing glucose, which can raise your risk for insulin resistance, type 2 diabetes, and energy crashes that hit at the worst times.¹ 

Let’s break down how jet lag and shift work impact your metabolic health, why blood sugar swings are part of the picture, and what science-backed strategies you can use to stay balanced, even when life doesn’t follow a 9-to-5 routine. 

Understanding Circadian Rhythms and Glucose Metabolism 

Your body’s internal clock is known as the circadian rhythm. It is a 24-hour cycle that helps regulate nearly every biological process, from sleep-wake cycles to hormone release, and also, how your body handles sugar. At the center of it all is your brain’s master clock, located in the suprachiasmatic nucleus (SCN), which syncs with cues like light and food timing to keep everything running smoothly. 

When your circadian rhythm is in sync, insulin (the hormone that helps your cells absorb and utilize glucose) is secreted in a predictable manner. In fact, studies show your insulin sensitivity is highest in the morning, making your body better equipped to manage carbohydrates earlier in the day.⁵ That’s why breakfast may be the best time for higher-carb meals for folks prone to insulin resistance.

But when your rhythm gets disrupted, say, from working the night shift, staying up too late, or flying across time zones, your body’s glucose regulation can suffer. Research indicates that circadian misalignment can contribute to insulin resistance, where cells fail to respond properly to insulin. This means your blood sugar stays higher for longer, increasing the risk of type 2 diabetes, cardiovascular disease, obesity, and fatigue.²

Not to mention, we don’t always make the healthiest choices when we experience sleep deprivation. Your routines influence your lifestyle, and even short-term disruptions, such as a red-eye flight or a few nights of poor sleep, can throw you off. And if these disruptions become chronic or ongoing? Your metabolism may remain dysregulated, making it more challenging to manage your blood sugar and energy levels over time. 

Jet Lag's Impact on Blood Sugar Levels 

If you’ve ever felt foggy, sluggish, or hungrier after a long flight, there’s a reason: jet lag puts your metabolic system under stress, increasing the likelihood of blood sugar swings and cravings.

Jet lag doesn’t just mess with your sleep schedule; it can throw your metabolic responses off, too. When you travel across time zones, your internal clock struggles to adjust to the new light-dark cycle. This disruption also affects the timing of insulin, cortisol, and melatonin, all of which play significant roles in regulating your energy and blood sugar levels. 

Your body may still be operating on your “home” time even though you’re eating, sleeping, and moving on a new schedule. This can lead to mismatched signals: you might be eating when your body thinks it should be resting, which blunts insulin sensitivity and makes it harder for glucose to move into your cells, also known as glucose intolerance. The result? Potentially elevated blood sugar levels, even if your food choices haven’t changed much. 

Several studies back this up. Research has shown that even brief periods of circadian misalignment, such as simulated jet lag, can impair glucose tolerance and reduce insulin sensitivity in healthy adults.³ Another study showed that participants who ate meals during their biological night had higher post-meal blood sugar spikes compared to those who ate the same meals during the day.⁴ 

Night Shifts and Their Effect on Glucose Control 

In addition to overhauling your schedule, working the night shift can also lead to metabolic changes, as your body is asked to function when it would typically be at rest. Your internal clock is disrupted when you work the night shift, and a cascade of metabolic changes occurs as a result, primarily affecting blood sugar and energy metabolism. 

Additionally, night shift workers often eat at irregular times, sleep fewer hours (and often less deeply), and may rely on quick, carb-rich foods for energy. These lifestyle changes can lead to poor insulin sensitivity, meaning your body isn’t as effective at clearing glucose from the blood. Over time, these irregular patterns may result in more frequent blood sugar spikes and crashes, even if your food choices don’t seem all that different to you. 

Numerous studies back this up. A 2018 paper that looked at over 70,000 night shift workers found that night shift workers have a 9% increased risk of developing type 2 diabetes, with the risk rising the longer someone works irregular hours.⁶

The researchers agree that the disruptions to melatonin at night and cortisol release during the day, as well as the changes in insulin resistance among night shift workers, all contribute to a greater risk. But it isn't all gloom and doom. You have some control over your lifestyle to help prevent diabetes and blood sugar ups and downs. 

What You Can Do to Mitigate Blood Sugar Disruptions 

If you’re navigating an unpredictable schedule after travel or working off hours, here’s what experts agree you can focus on for your metabolic health. 

• Meal Timing and Composition: Try to eat your meals at about the same times each day, even if your “day” happens overnight. The body’s internal clock thrives on routine, and regular eating patterns help regulate insulin release. Choose meals that are high in fiber and protein, which slow down digestion and help prevent blood sugar spikes. And when you can, practice avoiding heavy, high-carb meals right before sleep, as your body’s ability to process glucose is less efficient at night. 
• Sleep Hygiene: Even if you’re on a different schedule, prioritize getting enough quality sleep. Create a calm, dark, and cool sleeping environment. Use a face mask, blackout curtains, or white noise machines if you need help blocking out light and sounds. Additionally, maintaining a consistent sleep-wake schedule (even on days off) can help reset your circadian rhythm and support glycemic control. 
• Physical Activity: Daily movement is one of the most powerful tools you have for maintaining a healthy metabolism. Exercise improves insulin sensitivity and helps prevent the development of diabetes. Whether it’s a quick walk, a 10-minute strength session, or even a brief yoga stretch before bed, choose a time and workout that fits your schedule and stick with it.
• Monitoring and Medication: Don’t leave your blood sugar up to chance. Use continuous glucose monitors or regular finger sticks to track how your body is responding to disruptions. If you’re traveling across time zones or working through the night, discuss with your healthcare provider adjusting your insulin or medication timing to better match your altered schedule. 

Practical Tips for Travelers and Shift Workers 

Whether you’re catching a red-eye flight or clocking in for a night shift, there are simple, effective strategies to help support your body and keep your internal clock running smoothly.

For Travelers 

• Ease into your new schedule: A few days before departure, gradually adjust your sleep and meal times to align with the time zone of your destination. Even a one to two-hour adjustment can make a significant difference here. 
• Hydrate often and avoid dehydrating substances: Air travel can be dehydrating, and dehydration can worsen blood sugar control. Drink plenty of water and limit caffeine and alcohol intake, as they can interfere with both hydration and quality sleep. 
• Pack blood sugar-friendly snacks: Bring balanced snacks that combine carbs with protein or healthy fats, such as trail mix, jerky, or a nut butter sandwich, to help stabilize glucose levels on the go. 

For Shift Workers 

• Meal prep with blood sugar in mind: Planning meals and snacks ahead of time reduces the temptation to rely on convenient, fast food during overnight shifts. Practice including protein, fiber, and healthy fats in each meal you pack yourself. 
• Try light therapy: Using a bright, artificial light or a sun light at the beginning of your shift can help reset your circadian rhythm and signal to your body that it’s time to be alert. 
• Use naps strategically: A short nap (no longer than 30 minutes) before your shift or during a break can help improve alertness without disrupting your main sleep cycle. 

The Bottom Line 

Both jet lag and night shifts are internal clock disruptors; however, there are still steps you can take to protect your health. Hormones like cortisol, melatonin, and insulin are all affected when our schedules shift. Remember, keeping a regular eating schedule, drinking water, and practicing good sleep hygiene can help support your body when you’re off your typical circadian rhythm.