Is technology changing our circadian rhythm?

Well, it depends on what you mean by 'changing'. Our circadian clock is innate and modulated by millions of years of evolution. Technology is not changing the structure of the clock or how it operates, but does impact the clock in ways unlikely selected for by evolution. There are two main ways in which technology can impact the clock, directly through artificial light exposure, and indirectly through changing behavior that then leads to unusual patterns of light exposure. Light is mainly doing two things to the clock. It is setting the time of the clock and it is changing the amplitude or strength of the clock. Under a solar light-dark cycle without any artificial light, our clocks would be set to an earlier hour. With artificial light, our clocks are often set to a later hour. In and of itself, this is not a pathological event. For example, if your clock was set under a solar cycle such that sleep was predicted to occur from 8pm until 4am, but under an artificial light cycle to occur from midnight until 8am, that would be fine (from a health perspective). Under a solar cycle, once the sun goes down, you are relegated to stars, moonlight, and firelight (at best). With technology, once the sun goes down, you have artificial light as well as the behaviors that this enables. These behaviors, unfortunately, often engender erratic timing of sleep (and therefore light exposure). This will weaken (albeit, temporarily if you go back to having a regular light cycle) the amplitude of the circadian clock and lead to downstream negative health effects. It is often, though not necessarily, associated with curtailed amounts of sleep, which independently has negative health effects. So, is technology changing our circadian rhythm? From an evolutionary perspective, probably not so much. From a behavioral perspective, most definitely.