Are cortisol spikes really the enemy? You’ve probably seen countless social media posts warning about the dangers of cortisol ‘spikes,’ advising against morning coffee or certain workouts. But here’s where it gets controversial: as an endocrinologist, I’m here to tell you that cortisol spikes aren’t something healthy individuals need to fear—in fact, they’re a natural and essential part of your body’s daily rhythm. And this is the part most people miss: it’s not the occasional spike that’s problematic, but rather the sustained, long-term elevation of cortisol that can lead to health issues.
Let’s start with the basics: What is cortisol? Cortisol is a vital hormone that regulates metabolism, the immune system, and cognitive and emotional processes. It’s produced by the adrenal glands, which sit atop your kidneys, but its release is tightly controlled by the pituitary gland—often called the ‘master gland’—located at the base of your brain. Cortisol follows a strong daily rhythm, with levels naturally rising and falling throughout the day.
One of the most significant spikes occurs within the first hour after waking, known as the cortisol awakening response. This surge helps you feel alert and prepared for the day ahead. Interestingly, research shows that a higher peak in this response is linked to better coping abilities with physical and mental challenges (https://doi.org/10.1073/pnas.0605053103). Conversely, a blunted awakening response is associated with poorer health (https://doi.org/10.1016/S0306-4530(02)00008-2).
Throughout the day, cortisol levels gradually decline, reaching their lowest in the evening to promote sleep. However, when faced with stressors like intense exercise, tight deadlines, or illness, your body releases additional cortisol pulses. These spikes are protective, helping you stay focused, maintain blood pressure, and release energy when needed.
But what about coffee on an empty stomach? This is where opinions diverge. While some studies show that coffee can increase cortisol levels by up to 30% (https://pubmed.ncbi.nlm.nih.gov/8951977/), others suggest that for regular coffee drinkers, the effect may be minimal (https://pubmed.ncbi.nlm.nih.gov/16204431/). Timing seems to matter more than whether you drink it with food. For instance, habitual coffee drinkers who consume caffeine in the morning don’t experience significant disruptions to their cortisol rhythm, but drinking it later in the afternoon may contribute to higher cortisol levels throughout the day (https://pubmed.ncbi.nlm.nih.gov/16204431/).
Similarly, exercise timing plays a role. Studies indicate that working out earlier in the day leads to a steeper cortisol decline after waking and lower evening levels, potentially making it easier to fall asleep (https://pubmed.ncbi.nlm.nih.gov/37946447/).
So, when does cortisol become a problem? It’s not the occasional spike, but chronic, sustained elevations that are concerning. Conditions like Cushing’s syndrome (https://doi.org/10.1038/s41572-024-00588-w), caused by tumors in the pituitary or adrenal glands, lead to persistently high cortisol levels. Similarly, chronic stress (https://doi.org/10.1038/s41380-021-01224-9) and long-term use of cortisol-like medications (https://doi.org/10.1210/clinem/dgae250) can disrupt the natural rhythm, exposing the body to prolonged high cortisol without the usual fluctuations.
While smartwatches claim to monitor ‘stress’ levels, they do so indirectly via heart rate variability, not by measuring cortisol. Accurate cortisol testing requires sophisticated methods like urine, saliva, or blood tests. So, don’t panic if your watch flags high stress—it’s not the same as high cortisol.
Here’s the bottom line: Instead of worrying about cortisol spikes, focus on managing chronic stress and maintaining a balanced lifestyle. If you’re concerned about your cortisol levels, consult your doctor. And here’s a thought-provoking question for you: With so much emphasis on avoiding cortisol spikes, are we overlooking the importance of our body’s natural stress responses? Let’s discuss in the comments!
