Scientists have found that if people fall asleep later, usual time, during sleep and the next day their heart rate is well above the norm. The same regularities are found and when going to sleep more than 30 minutes earlier than usual, although in this case the pulse was returning to normal after a few hours of sleep. Article published in the journal npj Digital Medicine.
Numerous studies show how much sleep hygiene affects our health. Inadequate sleep duration increases the risk of cardiovascular diseases and obesity, but also lowers overall life expectancy. Adults scientists and doctors suggest sleeping 7-9 hours per night, but important not only the duration of sleep itself. Less studied is the impact on health of sleep, although all recommendations indicate that it is necessary to go at the same time. If the time bedtime changes from day to day and suffer from nervous system and metabolism. About the influence of how constantly the time when we have to sleep on the cardiovascular system, not much is known.
The key indicator for the health of the cardiovascular system — the heart rate at rest. High heart rate is associated with increased risk of death from all causes and from cardiovascular disease. This indicator is important in the dynamics: in health affects how it changes over time and with age and how quickly it returns to normal after recovery.
A group of scientists from the University of Notre Dame, led by Louis Faust (Louis Faust) recorded the pulse and the time of going to bed at 557 students using activity trackers (smart wristband). All were collected data for more than 255 thousand nights. Normal bedtime was calculated in each semester separately as the period 30 minutes before and after the mean time of falling asleep.
If the participants went to bed 30 minutes earlier than the usual time, their heart rate did not change. But falling asleep more than half an hour earlier than usual led to a significant increase in heart rate during the first hours of sleep, although the rate quickly returned to normal. On the seventh hour of sleep the pulse of those who fell asleep before was even lower than at the usual time of going to sleep.