Note, this is not a question about std::condition_variable::wait_for(). I know that can wake spuriously.
My program’s behavior suggests the answer to this question is Yes, but the STL documentation is quite clear for the condition_variable case. At least at cppreference.com, the correct answer for this_thread appears to be No.
Compiler is gcc 4.8.1, in case this is a defect.
The relevant sections of the C++ Standard (paragraphs [thread.thread.this]/7-9) do not mention anything about spurious wake-ups for std::this_thread::sleep_for, unlike e.g. for std::condition_variable::wait_for.
template <class Rep, class Period> void sleep_for(const chrono::duration<Rep, Period>& rel_time);7 Effects: Blocks the calling thread for the relative timeout (30.2.4) specified by
rel_time.8 Synchronization: None.
9 Throws: Timeout-related exceptions (30.2.4).
This implies that the behavior you are observing is non-conforming.