Measuring cortisol concentration in hair month-by-month two years retrospectively

Figures & data

Figure 1. The repeated measurements of hair cortisol over the 24-months sampling period. Mean and SE and outliers are shown.

Figure 2. Frequency of hair washing, those who reported they washed their hair every day had a significant negative slope whereas less frequent washing was associated with less negative slopes.

Figure 3. Illustrate original cortisol levels measurement 24 months retrospective for 10 random individuals of the total 48 participants.

Table 1. Characteristics of the study population.

Characteristics	N	%
Occupation
Student	27	56.3
Employee	21	43.8
Hair Colour
Brown	20	41.7
Blonde	24	50.0
Red	1	2.1
Black	3	6.3
Frequency of hair washing with shampoo
Every day	4	8.3
Every other day	29	60.4
Twice a week	15	31.3
Chronic diseases
Yes	9	18.8
No	39	81.3
Steroid-based medication
Yes	6	12.5
No	42	87.5

Table 2. Models of time trends and their moderation.

Model	Slope	95% confidence interval	p-value
1: Linear time only	0.91	−0.11, 1.93	0.08
2: Linear time	−0.33	−3.67, 3.02	0.8
2: Quadratic time	0.05	−0.08, 0.18	0.5
3: Life stress (yes or no)	−8.76	−14.05, −3.46	0.001
4: Life stress (yes or no)	−8.48	−14.63, −2.32	0.007
4: Linear time	−0.28	−3.63, 3.08	0.9
4: Quadratic time	0.05	−0.09, 0.18	0.5
5: Linear trend moderated by hair-washing frequency
Overall	–	–	0.007
Every day	1.0	–	–
3–4 times/week	0.42	0.05, 0.78	0.03
2 times/week	3.78	0.55, 7.02	0.02
6: Linear trend moderated by hair colour
Overall	–	–	0.02
Brown	1.000	–	–
Blond	2.67	0.63, 4.72	0.01
Red	0.20	−0.06, 0.46	0.1
Black	−0.18	−0.62, 0.27	0.4

Data availability statement

The datasets generated and analyzed during the study are available at https://doi.org/10.48360/zw8d-qr94