Table 1.

Questions used in the study

Questions	Answers	Categorized as
Total sleep duration, TSD: How long do you usually sleep at night? How long do you usually sleep during the daytime?	The patient wrote the number of hours and minutes for both questions freely. The night and day sleep were summed into TSD and compared with the Health 2000 study question ‘How many hours do you sleep per day?’	Responses that had missing or unreasonable answers to the sleep duration question (TSD < 2 hours or ≥ 18 hours) were excluded. Long SD was defined as sleeping 10 hours or more and short SD as sleeping 6 hours or less.
Difficulty initiating sleep, DIS: Do you have difficulties falling asleep without sleep medication?	Not at all, sometimes, often, and nearly always.	DIS was defined as ‘often’ and ‘nearly always’.
Early morning awakenings, EMAs: Do you wake up during sleep at night or very early in the morning?	Not at all, sometimes, often, and nearly always.	EMAs were defined as ‘often’ and ‘nearly always’.
Fatigue, FAT: Do you consider yourself to be fatigued more often than other people of the same age during the daytime?	Yes, nearly always; yes, often (at least weekly); no; I cannot say.	FAT was defined as ‘Yes, nearly always’ and ‘yes, often’.
Sleep quality, SQ: How well have you slept during the last month?	Well, rather well, neither well nor poorly, rather poorly, poorly.	Poor SQ was defined as having slept ‘rather poorly’ or ‘poorly’.
Subjective health: Assess your own current state of health by entering the number that best corresponds to your current state of health.	Numeric scale from 0 to 10.	—
Health-related quality of life, EQ5D Please tick the one box that best describes your health today.	3-level answer categories for mobility, self-care, usual activities, pain/discomfort, and anxiety/depression	Converted to a linear 0–1 variable based on country-specific conversion factors
Mental Health Inventory–5, MHI–5 Please tick the one box that best describes your health today.	5 questions on mental health and psychological distress	The scores from the five questions were converted, added together, and used as a linear variable.
Subjective cognitive functioning Focus: How well are you usually able to focus? Memory: How do you rate how your memory functions? Learning: How do you rate your ability to learn new things?	Very well, well, satisfactorily, poorly, and very poorly	Poor subjective focus, memory, or learning was defined as ‘poorly’ or ‘very poorly’. A combined dummy variable named ‘poor subjective cognition’ was created which was defined as having answered ‘poorly’ or ‘very poorly in any of the three questions.