Dear Mani, 

E.g. when stress hormons are likely to excrete (in Sweden it would be at 8h in the morning and 17 in the afternoon with gender differences). Probably best to do a qualitative study with a smaller group of people for example male informants ( 20-25 years) write down their mood on a, e.g., 7 point scale,  at 8h AM,  noon, at 3, at 6 and at 9 PM seven days a week to get some idea for a bigger study.

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Dear Beatrice,

Thanks for your time to consider this question.

Let me check if I have understood you correctly:

1- You believe, mood swings are caused by change in stress hormons?

2- In Sweden (Gender aside), you believe mood swings happen in specific hours in a day? e.g., If someone's mood is negative, then it's more likely his/her mood would change to positive at 8AM or 5PM (In average)?

3- Does it mean that, a healthy person in Sweden should experience mood swings about twice a day?

Yes, I think you are at risk to get into a family discord when your cortisol mirror is at its highest point. 

Biol Psychol. 2014 May; 99(100): 34–40.

doi: 10.1016/j.biopsycho.2014.02.010

PMCID: PMC4031630

The relationship between cortisol responses to laboratory stress and cortisol profiles in daily life

Tara Kidd,⁎ Livia A. Carvalho, and Andrew Steptoe

 Dear Beatrice,

Thank you for your informative answer.