The Damage of Sleep Debt
With these three perspectives in mind, we can turn briefly to the specific impacts that take place if we don’t get enough sleep. The sleep debt accumulates, and, as a result, a lot of bad things can happen. There are many well-established relationships between sleep and physical health, mental health and cognitive functioning. The physical consequences of inadequate sleep and the accumulation of sleep debt include obesity, diabetes, vulnerability to infections, and cancer. The complete list is much, much longer. We can also point to the accidents and performance decline that comes with lack of sleep. Remember falling asleep at the wheel?
When we turn to the consequences in terms of mental health, we can identify a list that is just as disturbing. First and foremost is the relationship between sleep debt and depression. There are many reasons to believe that the increase of depression in the United States is related to a reduction in the amount and quality of sleep among our citizens. Sleep debt also relates to our ability to manage anxiety, control our rage and remain emotionally stable and “emotionally intelligent” when relating to other people. Perhaps of greatest importance is the strong relationship between sleep debt and suicide attempts (and tragically successes). The bottom line: we can die from sleep debt.
What is High Quality Sleep?
The usual concern about quality of sleep centers on the number of hours needed between hopping in bed and bounding up in the morning. As we all know, this number usually hovers between six (at the low end) and eight (at the high end). We also know that most Americans (and those residing in many other countries) tend to get too little sleep – often 4-5 hours per night. The sleep debt accumulates, like the national financial debt, and the alarms periodically sound in the national media: “We need to get more sleep!”
To use a standard dramatic gesture: “Not so fast!” High quality sleep is defined not just by number of hours in bed, but also by two other factors: (1) depth of sleep, and (2) amount of sleep disruption. There is even a fourth factor (amount of “sleep” engaged at times other than at night) which I will introduce in my further essays. . Let’s briefly look at each of the two major factors.
Depth of Sleep
First there is depth of sleep. When I was working in the dream lab during my younger years, I directly witnessed the movement of our subjects through four stages of sleep. Typically, when we fall asleep, we move slowing down through what are called stage one, stage two and stage three sleep—to arrive at stage four. This stage is often called delta sleep because the brain waves (EEG recordings) resemble the Greek letter delta (slow upward spikes). This is the stage where our body seems to be doing a whole lot of physical restoration. It is sometimes called “the working man’s sleep” because of this supposed physical restoration. Unfortunately, as we grow older, this fourth stage of sleep becomes less frequent and will often vanish all together by the time we hit our 50s. My own 78 year old body hasn’t been visited by stage four sleep for many years!
