Although the Tannaim establish early times for the understanding of the time of going to bed according to their mesora for krias Shma, how do we deal with the fact that nowadays we all know that zman shechiva/beshachbecha is always late? No one in our societies goes to bed according to the times of the Tannaim. The usual time is 10 or 11 at night! Why we wouldn't we say that zman krias Shma doesn't start before 10pm, our time for being yotsi the mitzva of krias Shma??!
David Goldman, USA
The Mishnah Berurah (OC 235:1) writes that one cannot say Keri'as Shema before three small stars appear because, before nighttime, it is not yet the time for lying down. This implies that in the daytime it is unnatural to sleep on a regular basis while there is nothing unnatural about sleeping in the early night even in contemporary society. Even though electric lighting has made the prevalent custom be to not go to sleep early, this is merely because of accepted practice, not because of a change in nature. If there is a power cut, people will go to bed earlier. Also, people who daven at "Hanetz" get up early and therefore go to bed early, as do people who need to start their workday very early.
In short, it is a natural thing sometimes to go to sleep soon after the stars come out, so even though the invention of electricity has meant that most people do not usually do this, this does not change the Halachah.
Kol Tuv,
Dovid Bloom