• weight, kg
  

The study is aimed to check a preliminary evidence that bright light may help to lose weight in obese people (Thor Helge Bergan, Norvey, 2002, unpublished). Subjects: ageg 20-65 y, BMI > 30, non-seasonal (SPAQ score <8, no seasonal problem), in good general health, with regular sleep from 22:00-1:00 to 6:00-9:00. Study season: November-April. Placebo-controlled, single-blind, crossover. At least 1 mo between two arms; at similar phase of menstrual cycle (if present). If could not complete at the first year, the second arm is to be done the next winter. Intervention: for 3 weeks each morning (at least 18 days) starting between 6:00-9:00. Seating, distance between the face and device is 41 cm, for 30 min. Lightbox - during one arm, deactivated ioniser - during another arm, in alternated order. Diet: a target amount of kcal per day is calculated based on age, weight and gender (WHO), e.g. for a woman 40 y ang 80 kg it is 1502 kcal per day. Food content - is also as recommended by WHO. Food distribution over day - usual for the particular test subject but constant over sessions. Food diary is completed daily and subjects calculate kcal themselves based on a Table of kcal. Outcomes: Weight is measured a day before and day after the 3-week session, during a visit to doctor, and also at home every week (to get a dynamic). Motivation and Expectation are rated by 3-point scales, in a Diary, at the beginning of each session. A general feeling (mood, activity, and appetite) - by a VAS-like 10-points scale every week. At the end of each arm the "Easiness of dieting" scale and Adverse event(s) are completed. In the diary, there are also columns for sleep on - off times, intervention time, duration, and distance, number of kcal. A total number of subjects to complete the study is 40.