Sleep, Cortisol, and Blood Sugar - Oh, My!

Last week we looked at the relationship between cortisol and blood sugar and how the stress response impacts so many aspects of our lives. In that article, I hinted at the connection between sleep and blood sugar dysregulation, and today I'd like to give you the low-down about how sleep is a driver in that process.

Cortisol curve

The Science Behind Sleep, Cortisol, and Blood Sugar

We tend to think of sleep as a passive state, but it’s actually an incredibly dynamic process that affects nearly every system in the body. One of the key players in this process is cortisol, the stress hormone we discussed last week. Cortisol follows a natural rhythm, peaking in the morning to help us wake up and gradually declining throughout the day. Picture a ski slope, where you’re standing at the top at wake-up and skiing downhill throughout your day. As cortisol levels drop, melatonin, the sleep hormone, rises, helping us feel tired and ready for bed.

But here’s where things get complicated—when we don’t get enough quality sleep, this rhythm gets disrupted. Poor sleep leads to higher evening cortisol levels, making it harder to fall and stay asleep. At the same time, elevated cortisol can cause blood sugar imbalances by signaling the liver to release glucose into the bloodstream. This means that a restless night can leave you waking up groggy, craving sugar, and on a blood sugar rollercoaster all day long.

How Poor Sleep Affects Blood Sugar and Overall Health

When sleep is compromised, it sets off a chain reaction in the body:

• Increased cravings for sugar and processed carbs – Your body is looking for quick energy to compensate for fatigue.

• Higher insulin resistance – Over time, poor sleep makes it harder for your cells to respond to insulin, leading to metabolic issues.

• More stress and inflammation – Chronic sleep deprivation keeps cortisol high, increasing systemic inflammation and worsening stress.

• Disrupted hunger hormones – Leptin (which signals fullness) decreases, while ghrelin (which signals hunger) increases, making overeating more likely.

  
  

Simple Steps for Better Sleep and Balanced Blood Sugar

The good news is that improving sleep quality can help regulate cortisol and stabilize blood sugar. Here are some practical strategies:

1. Make Your Room Dark and Cool

   • Darkness signals melatonin production, while a cool room (around 65°F) promotes deeper sleep.

2. Establish an Evening Wind-Down Routine

   • Begin your bedtime routine early by washing up right after dinner and changing into your comfy pjs or loungewear. This way, once you get sleepy all you have to do is climb into bed and turn out the light.

3. Become Aware of Your Circadian Rhythm

   • Pay attention to what time you start feeling sleepy and ride that wave. Plan to make that your regular bedtime.

4. Limit Screens and Overhead Lights in the Evening

   • Blue light from devices interferes with melatonin production. Use warm, dim lighting and avoid screens at least an hour before bed.

5. Avoid Eating 2-3 Hours Before Bed

   • Late-night eating can spike blood sugar and disrupt sleep. If you need a snack, opt for something with protein and healthy fats.

6. Prioritize Protein and Healthy Fats at Dinner

   • A balanced meal helps keep blood sugar steady overnight, preventing middle-of-the-night wake-ups due to glucose drops.

7. Incorporate Deep Breathing or Meditation Before Bed

   • Activating the parasympathetic nervous system (your “rest and digest” state) can help lower cortisol and ease you into sleep.

8. Practice Gratitude

   • Reflecting on positive moments from the day can shift your mindset and reduce stress before sleep.

9. Get Sunlight Exposure at Key Times

   • Morning, noon, and dusk sunlight exposure helps regulate your circadian rhythm and supports healthy cortisol and melatonin cycles.

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Final Thoughts

Improving sleep isn’t just about feeling more rested—it’s a powerful tool for regulating stress, stabilizing blood sugar, and enhancing overall well-being. Small changes in your evening routine can make a significant difference over time.

Next week, we’ll explore how chronic stress and poor sleep contribute to inflammation and immune system dysfunction. In the meantime, what’s one change you can make to improve your sleep this week?