Sleep debt or sleep deficit is the cumulative effect of not getting enough sleep. A large sleep debt may lead to mental or physical fatigue. –wikipedia
This term "sleep debt" was prposed by Professor William C. Dement at Sanford. Nobody likes "debt" in any area. I think this is a good naminig to alarmingly emphasize how important to have sufficient sleep.
Today I would like to explain about the concept of sleep debt and how difficult to return this debt.
Why it is a problem?
One of the trick characteristics for sleep debt is that we tend not to recognize this cumulative sleep debt. We might think we sleep sufficiently everyday and there is no sleep issue. However, there might be a chance that you do have slightly lower than you need everyday. That difference would be accumulated like a snow ball of financial debt with interest. Without our noticing, our performance of work or chore jobs are decreased. In the worst case, you might be dead due to the mistakes or sickness trigered by lack of sleep.
One research by University of Pennsylvania (The cumulative cost of additional wakefulness) showed one intriging result:
- The performance of those who stay over the night dropped sharply
- The performance of those who sleep less (6 hours) everyday for 2 weeks eventually became equivalent to the one of those who stay over the night on the 2nd day.
How to detect sleep debt?
It is actually difficult but if you need to sleep a lot on weekend or your days off, this could be the indicator of sleep debt. Your brain and body thrive to return the sleep debt cumulated during the weekdays.
To test it, you should sleep in a completely dark room without PC or smartphones' screen. When you wake up but still feel like sleepy, sleep again until it goes away. If you observe the increase of sleep time more than 2 hours, you need to re-consider your sleep schedule.