Constant fatigue is a very uncomfortable, but very common, physical state. YouGov’s latest research shows that a significant number of Americans don’t feel fully rested for most of the week. Only 15 percent report not waking up feeling tired even one day a week. But lack of sleep is just one – and the most obvious – reason why you feel lethargic as soon as you open your eyes. Other sneaky factors sapping your energy can be as simple as clutter in your office or keeping the temperature in your home too high.