nighttime temps are always lower
Sorry for an indirect response but:
Search 'Greenhouse DIF' or 'Greenhouse zero DIF'
To answer your Q in a nutshell; suboptimal growth. Not catastrophic, not markedly so, just not optimal.
.
.
Why spread false info? Stem elongation is generally reduced when day/light time temps are closer to equal or less than night. Temperature manipulation can be quite beneficial.