Did you know that if you deprive a fruit fly of sleep, it experiences cognitive impairment (as measured by things such as how long it takes the fly to learn where the sugar is, and how quickly the fly forgets)? Even fruit flies with their very little brains need their beauty rest. Interesting note: birds can sleep with one brain hemisphere at a time, while the other hemisphere stays awake and alert. Dolphins and seals do this too.
We know that sleep is crucial to our health, but we probably underestimate how important it is. We think we can get away with 6 or 7 hours per night because we think that amount is so close to what we need that it shouldn’t matter. After all, the only symptom we seem to feel is a little bit of tiredness, and after we get up in the morning (and drink caffeine) that quickly fades.
America is actually full of people with chronic sleep deprivation.
A common myth about sleep is that getting just an hour less than normal per night won’t affect you. We’ve heard that we need about eight hours of sleep; however, most people think of those 8 hours as a luxury, unrealistic in their current life. Some people even think of an eight hour night’s sleep as near to indolence, much less as actually healthy. But the fact is that getting even one hour less sleep per night will affect your ability to think properly and respond quickly to problems. It also compromises your cardiovascular health, your balance of energy and your immune system’s ability to fight infection.
We adapt to how tired we are
We may think we can adapt to simply sleeping less, but what we are adapting to instead is how tired we are. We become quite good at not knowing, or noticing our fatigue. We may get used to not sleeping enough for months or even years, and all this time, continue to believe that we are doing okay. But then we are surprised when accidents happen because our subjective judgment all along was simply that we weren’t that tired.
You cannot adapt to getting less sleep than you require.
You may think you can, but you are just not aware of how impaired you are. Your brain literally remembers how long you’ve been asleep and awake and keeps track of this for weeks, and “…the bigger our aggregate sleep deficit, the faster our performance deteriorates, even after a good night’s rest.” Chronic sleep loss means that even when you have a good long night’s sleep, you will still tire much faster than you would if you weren’t under a sleep debt.
Another reason people think they are less tired than they actually are (other than, of course, our natural tendency to assume we are right and we know everything) is that we tend to judge how tired we are based on how we feel between 3 and 7 pm. Since we are hitting the high point of our circadian cycle at that time of day, we naturally feel better. That’s because melatonin levels are at their lowest, and this phenomenon essentially masks the effects of sleep loss.
What’s your sleep debt?
To make matters worse, the bigger our sleep debt, the less capable we are of understanding that we have a big sleep debt. Most of us can hardly remember what it’s like to feel fully rested, so we start to believe that we are more fully rested than we actually are.
The National Sleep Foundation (NSF) reports that at least 40 million Americans have a sleep disorder, and that 60% of Americans report sleep problems at least a few nights per week. The numbers are worse for children—nearly 70% experience sleep problems at least a few nights per week.
Older people need sleep too
We often think that older people need less sleep, but this is yet another myth that simply isn’t true. Older people often get less sleep, but they still need just as much sleep as they did earlier in their lives. The ability to slide into deep, restful sleep stages decreases with age. A more fragile sleeper is more easily disturbed by things such as noise, light, pain and any special medical problems that may also contribute to sleep difficulties.