For those of us that have trouble finding the time to get the sleep we need because of busy lives or that struggle to fall or stay asleep at night, the idea that we can reverse any damage done by paying back this “sleep debt” has always provided some hope. The idea is pretty simple. Think of your body as a bank where you deposit and withdraw energy as you move through your life. One of the ways that you make deposits to offset the withdrawals is by sleeping. But, when you don’t make enough deposits, it isn’t like your body can just stop performing vital functions so you wind up in sleep debt. This debt represents the difference between how much sleep your body needs and how much sleep it has gotten. Most people believe that it is ok to skip sleep on one night because you can always make it up – or pay it back – at some future time.
But one research team wanted to know if there was any truth to back up this widely held belief that many insomniacs and parents with small children have held on to as a small kernel of hope against the devastating health effects of prolonged sleep deprivation. Their findings were published in the American Journal of Physiology late last year and indicate that it may be time to shift the focus from paying back to paying forward.
The team wanted to know if sleeping extra in order to pay back sleep debt actually helped alleviate the symptoms associated with lack of sleep. Participants spent 13 nights in a sleep lab having their sleep monitored. For the first four nights, all participants slept a full 8 hours. This made it possible for the research team to get a baseline of the key factors they would be tracking, all of which are known to become degraded when a person is sleep deprived. These factors were attention, stress, daytime sleepiness, and levels of low-grade inflammation.
With the baseline set, participants were then restricted to only 6 hours of sleep per night for 6 nights. In theory, this left them with a 12 hour sleep debt. Over that timeframe, the same factors were monitored. As expected, participants showed degradation in attention, increased daytime sleepiness, and higher levels of inflammation based on blood tests related to a biomarker associated with tissue inflammation. However, they were surprised to find that the levels of cortisol in the participant’s bodies remained constant throughout the sleep deprivation period. This is the hormone associated with stress which has previously been shown to increase when people are not getting the sleep they need.
Next, participants were allowed to sleep for 10 hours a night for three days, effectively paying back 6 of those 12 missed hours. If the sleep debt theory is true, the participants should have experienced increases in attention, decreases in daytime sleepiness, and lower levels of the tissue inflammation biomarker. However, only the second two proved to be true. After the payback period, the attention levels of the participants did not return to their baseline levels. This is a significant finding because decreased attention is one of the most immediate and dangerous problems encountered when people do not get enough sleep. It increases the risk of being involved in a drowsy driving accident and degrades performance across every area of life. The teams concluded that the unexpected cortisol level results were likely caused by pre-existing sleep deprivation and that more research would be needed into the sleep debt theory.