The phrase "heightened levels of" is correct and usable in written English.
It is typically used when referring to an increase in an intensity, volume, or frequency of something. For example, "The protests have caused heightened levels of tension in the city."
One of the less remarked-upon aspects of autism is heightened levels of sensory sensitivity.
They have won many tight games but you can't detect heightened levels of efficiency in front of goal.
"Throughout spring 2014, there were heightened levels of both online and offline incidents reported to Tell Mama.
It was a night, as the Arsenal manager, Arsène Wenger, had stressed, for balance and heightened levels of concentration.
They try to persuade people that the world has changed, requiring heightened levels of security in everything from cyberspace to buses.
But boredom is a prerequisite to attaining heightened levels of perception, argues an unsigned, online article on psychic development (found at www.newvision-psychic.com/magazine/698/notdoing.html).html
"The cold can also contribute to heightened levels of respiratory illness – particularly among the elderly and those with long-term conditions.
Other signs of inflammation included heightened levels of inflammatory signaling molecules, called chemokines and cytokines.
The relationship between hostility and heightened levels of glucose may be evident even in childhood and adolescence.
The new provisions include heightened levels of disclosure from companies, as well as income/net-worth caps on the maximum amount retail investors are permitted to invest.
Adolescent aggressive victims are youth who demonstrate heightened levels of aggressive behavior and are frequently victimized by others.
