When we experience stress, it can often lead to a series of hormones being released in the body. New studies have suggested that we actually have a vulnerability to stress as the day progresses. Our body may actually react more strongly to acute psychological stress in the evening compared to stress that we might experience in the morning.

Studies conducted by Japan’s Hokkaido University are suggesting that even with normal work hours and sleeping habits, we react differently to acute psychological stress later on into the evening. In a study conducted on 27 healthy young volunteers as they went about their normal routine, it was determined that hypersonic pituitary adrenal (HPA) axis changes occurred, leading to different responses for acute stress as the day progressed.

The HPA axis connects directly to the central nervous system and endocrine system in the body. Cortisol is the primary stress hormone that gets released every few hours when the HPA gets activated due to a stressful event. Stressful events will directly provide us with energy and activate a fight-or-flight response. The circadian clock within our body can actually work to maximize these responses and make sure that a fight-or-flight response can get supercharged during specific hours of the day.

Throughout the experience, the research team worked to measure the cortisol levels in volunteers at their baseline when they first woke up. Volunteers were divided into two groups where one group was exposed to stress in the morning and another group was exposed to stress in the evening, around 10 hours after they’d been awake.

Volunteers that were taking the test in the evening continued to experience a much higher heart rate than individuals that were taking the test in the morning. It seemed as though the participants that were exposed to stress in the morning had a much easier time activating their HPA axis within the sympathetic nervous system. Individuals that were exposed to stress in the evening experienced a vulnerability in preventing extreme stress within their system.

The largest issue with evening stress now that we know we are susceptible to it and that it can prevent sleep. When we get worked up before it’s time for our bodies to go to sleep, it often leads to fits of insomnia and issues when it comes to sleeping. As we know that our biological clock can have a large effect on our ability to manage stress, the more time that we continue to change our city and rhythm and go without sleep, the worse our reaction to stress can be.

If you have ever felt extremely frazzled as a result of several days of not sleeping, you have likely experienced this connection in action yourself. Recognizing that we can be more susceptible to stress in the evening can help us prepare our schedules accordingly. If you have some stressful activities planned for the day, it could be a wise idea to schedule these actions for the morning where your body can be better equipped to handle the extra stress.