The famous chossid and mentor, Rabbi Mendel Futerfas related this episode:
Once, a chossid of the fifth Lubavitcher Rebbe, Rabbi Sholom Dovber asked him the following question:
“What should I do about the fact that when I begin the nightly recitation of the Shema, I am so tired that I doze off while I am saying it?”
The Rebbe responded:
“You should rest for an hour or two, then awaken and recite the Shema properly.”
Again, the chossid asked:
“What if I remain asleep until morning?”
The Rebbe responded:
“In such a scenario, you should read the Shema early in the morning. It is clear, that no matter what, you should recite the Shema—if not the entire day does not run as it should.”
For a chossid, the nightly Shema is a time for introspection and an accounting of the previous day. If one does not make a reckoning for his actions, he will not know what there is to fix.