For this study, researchers wanted to better understand the connection between sleep timing and heart disease. To do this, they analyzed existing sleep data from just over 88,000 adults in the U.K.
The participants’ sleep onset (when they fell asleep) and wake-up times were collected over a seven-day period using a device worn on their wrists called an accelerometer.
The researchers also completed various assessments and questionnaires to record things like demographics, health, and lifestyle factors. After a follow-up period of 5.7 years on average, they revisited the participants looking for heart disease-related diagnoses, such as heart attack, stroke, heart failure, etc.