"People of different kind" or "People of different kinds"
english.stackexchange.com › questions › 321119Apr 23, 2016 · As kind is a countable noun (used in this sense), it must have an article when singular. So it is either people of different kinds, or people of a different kind. However whilst the former is used to refer to two or more kinds of people e.g. The anti-EU voters comprise peoples of many different kinds, the latter is used to apply to a single kind of people, who are different to some reference group, or groups e.g. UKIP voters are people of an entirely different kind to all others.
The Different Kinds of Sleep - BrainFacts
www.brainfacts.org › The-Different-Kinds-of-SleepMar 20, 2012 · These four types of brain waves, and others discussed below, are important criteria that have been used to define four distinct stages of non-REM sleep. Obviously, falling into a deeper and deeper sleep as the night progresses is actually a gradual, continuous process, but these four stages still provide a convenient means of describing the ...