Atopic dermatitis is a chronic disease with a high impact on patient's quality of life. Nocturnal pruritus is one of the main symptoms affecting quality of life. Treatment efficacy is generally measured by healthcare professionals during consultations with both questioning and visual examination of the lesions. Quality of Life (QoL) can also be evaluated retrospectively with the Dermatology Life Quality Index (DLQI) scale. Collecting data retrospectively introduces a significant recall bias that can be addressed by collecting data in Real World (RW). Real World data collection is prospective and take place within the patient's own environment. While data collection is generally done with diaries, it has been demonstrated that smartphone and connected devices were able to produce more precise and granular data than traditional methods.

The main objective of the study is to demonstrate a medical hypothesis using a wristband actigraph: patients with moderate to severe atopic dermatitis have a poorer quality and quantity of sleep than healthy subject.

Secondary objetives are to assess the interest of a smartphone application in evaluating the quality of life of patients with moderate to severe atopic dermatitis in regard of those of healthy volunteers.

Inclusion Criteria:

Patients :

• Subjects using a smartphone running Apple operating system (iOS 7 and above) or Android (version 2.2 and above)
• Subjects agreeing to wear the actigraphy wristband at night
• Subjects 18 years old or older
• Subjects affiliated to French Health Insurance
• Subjects treated for moderate to severe atopic dermatitis or atopic dermatitis exacerbation* *The stage of the atopic dermatitis will be assessed by using the Eczema Area and Severity Index (EASI), Body Surface Area (BSA) and Investigator Global Assessment (IGA). The EASI is an investigator-assessed instrument measuring the severity of clinical signs in atopic dermatitis. The EASI was identified as one of the best-validated outcome measures for atopic dermatitis.

A moderate to severe atopic dermatitis corresponds to:

• Eczema Area and Severity Index score ≥ 7.1
• Investigator Global Assessment ≥ 3
• Body Surface Area ≥ 10

Healthy volunters :

• Subjects using a smartphone running iOS (iOS 7 and above) or Android (version 2.2 and above)
• Subjects agreeing to wear the actigraphy wristband at night
• Subjects 18 years old or older
• Subjects affiliated to French Health Insurance
• Subjects without a dermatology disease

Non inclusion Criteria:

• -Illiterate subjects

• Subjects not proficient in French

• Subject with a primary insomnia*

  *Insomnia, sleep apnea and hypersomnia will be evaluated with respectively 3 tests:

• Insomnia Severity Index (ISI);

• Berlin Sleep Apnea Scale;

• Epworth Scale

• Subjects treated by hypnotic drugs

• Pregnant woman

• Subjects under guardianship

Exclusion criteria:

If a participant is taking hypnotic treatments during his study participation, he will be excluded from the clinical trial.