Ever get to the end of your day and find that you're just no longer able to deal

You might think this is because you're just exhausted or over it or hearing the call of happy hour, but it could really be that your body releases less of the hormones that help you respond to stress in the evenings. 

New research from Hokkaido University in Japan finds that when stress hits in the morning, the body delivers an extra jolt of the stress hormone cortisol to the system. However, when study participants were faced with the exact same type of stressful situation (giving a presentation and doing some mental calculations) in the evening, the body did not get the same cortisol-based boost of energy to face the challenge.

"Our study suggests a possible vulnerability to stress in the evening," explained physiologist Yujiro Yamanaka.

Yamanaka and his colleagues conducted a study involving 27 volunteers and measured their cortisol levels in response to stressful situations at different times of day. The results are published in the journal Neuropsychopharmacology Reports.

You are already primed to deal with stress better in the morning, as the brain's master circadian clock that regulates hormone levels makes sure cortisol levels are typically higher at the start of the day. 

The body has other ways of addressing stress, namely the sympathetic nervous system, and the researchers found that system does not vary in how it responds to stressors in the morning versus the evening.

But if you've got some unpleasant business or a high pressure situation you need to deal with, probably best to schedule it before lunch if you can.

There is, of course, the all-important caveat that results may vary. Or, as Yamanaka puts it:

"It is important to take into account each individual's unique biological clock and the time of day when assessing the response to stressors and preventing them."

Fair enough, but I still prefer to get the worst bits of the day over with first thing. You can decide for yourself what it means that I wrote this all in the evening.