There are some general properties shared by all forms of electromagnetic radiation: 1  It can travel through empty space. 2  The speed of light is constant in space. 3  A wavelength of light is defined similarly to that of water waves---distance between crests or between troughs.
The Parkinson Handbook Fatigue and Parkinsonâs Disease. Fatigue due to Depression-Depression is common in people with Parkinson's disease. It occurs in about 40% of the patients. Fatigue is a typical symptom of depression and is often reported as a lack of motivation or a loss of energy.
11 Causes of Fatigue. There are many possible causes of fatigue with the majority of diseases often resulting in general malaise or extreme tiredness. However, fatigue can also occur in otherwise healthy individuals as an expected response to physical and mental exertion.