Table 1 Inclusion and exclusion criteria

Age ≥18 years and ≤35 years

Study participants who cannot cooperate to the test.

Speak and understand the Danish language

Study participants who have a weekly intake of >21 units of alcohol, or a have consumed >3 units of alcohol within 24 h before study day.

Healthy male

Study participants with a substance abuse, assessed by the investigator.

Signed informed consent

Study participants, who have consumed analgesics less than 3 days before study day.

Study participants, who have consumed antihistamines less than 48 h before study day.

Study participants who have consumed antidepressant medication during the last 30 days before the study

Study participants who have consumed prescription medicine during the last 30 days before the study.

Study participants with neurological illnesses.

Study participants with chronic pain

Study participants with psychiatric diagnoses

Study participants with tattoos on the extremities

Study participants with eczema, wounds or sunburns on the sites of stimulation.

Study participants with a Body Mass Index of >30 kg/m² or <18 kg/m²