"it's so tiring to go to work every day... Today is finally Friday! I must catch up on some sleep...Don't wake me up until I get up by myself!"
Does this happen repeatedly every weekend? It’s just like an infinite loop - working late and waking up early during the week, while waking up so late on weekends.But no matter how much sleep you get on weekends, you are still so tired and always feel that you haven’t got enough sleep.If you have such a situation, then this article is your savior! Keep reading!
Sleep is a subject that has been studied for a long time. If you want to understand sleep in depth, you need to understand at least three clocks (or translated into rhythms) that affect our lives: Social Clock, Sun Clock, and Circadian Clock. The relationship between these three kinds of clocks was almost synchronized in the unindustrialized society in the past, because in the era with inconvenient lighting tools, the time of sunshine represented the working time of human beings and the time of social activities. Corresponding with the sunrise and sunset, humans got up and slept regularly. However, with the invention of the light bulb in modern times, humans began to have artificial lighting in addition to sunlight. Now with advanced technology, 3C products are another kind of lighting sources. In the end, the three kinds of human clocks began to show huge gaps between each other, and these gaps changed many times in a short period of time, which may affect human health.
Among sleep issues, one of the most frequently discussed problem isSocial jet lag (SJL), which means:The difference between "the midpoint of a holiday sleep" and "the midpoint of a weekday sleep". Generally speaking, the value of this social jet lag is positive, because usually holiday sleep will take longer than weekday sleep.A large retrospective studyshowed that the proportion of population with social jet lag within 2 hours is about 80%, and only very few people sleep longer on weekdays than on holidays (which will making the value of SJL negative):
In addition,Chronotype seems to be related to Social Jet Lag."Chronotype" represents one's preference for activity time. Those who prefer to get up early for activities and go to bed early are of "early chronotype / morningness", and those who prefer to get up late for activities and sleep late are classified as "late chronotype / eveningness". In previous studies, it was found that: The more preference for Late Chronotype, the greater the Social Jet Lag. However, whether this relationship is affected by the difference in sleep time or sleep deprivation during normal days remains to be elucidated in further researches:
After discussing so much data about social jet lag, what impact will social jet lag have on human health?
In fact, many studies have found that social jet lag is associated with certain unhealthy living conditions or diseases. In terms of lifestyle, the greater the social jet lag, the greater the worse eating habits, the higher the chance of becoming a smoker, the worse the academic performance, and the more aggressive physical and verbal behaviors. In terms of disease, social jet lag is significantly associated with metabolic syndrome and obesity. The above shows the potential health risks of social jet lag. However, studies have also shown that, for people who usually have insufficient sleep, there will be a higher mortality rate if they do not catch up on any sleep on holidays.
In fact, in today's workplace, there are indeed many job requirements that prevent workers from having regular and complete sleep, such as medical staff, security, drivers, etc. however, sleep deprivation and social jet lag do have potential health risks. Therefore, we recommends that, if life permits, please have at least 6 hours of complete sleep, regular sleep timing, and limit catch-up sleep up to 2 hours on holidays. If you usually lack sleep due to work needs, it is recommended that catch-up sleep is still required on holidays. The length of catch-up sleep depends on the situation, and please try to limit it up to 2 hours.
Finally, we want to remind you that, due to individual differences, the length of adequate sleep is different to everyone, which is about 5-9 hours a day. We recommends that you can use the sleep data when you were having regular life schedules and good mental states as references!
〈The author is former Attending Physician in National Taiwan University Hospital, and Master of Science from National Taiwan University〉