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.
Chronic fatigue syndrome (CFS) is a disorder that causes extreme fatigue. This fatigue is not the kind of tired feeling that goes away after you rest. Instead, it lasts a long time and limits your ability to do ordinary daily activities.