Flaxseed oil seems to have detectable effects within hours. For example, I increased the dose in the evening and my balance was better the next morning. To get some sense of the time course of the effect, I varied the time of day that I took the flaxseed. I usually took it around 10 pm; I tried 10 am instead. I continued to test my balance around 7 am.
Here are the results from an ABA experiment.
Taking 3 tablespoons at 10 am produced better results than taking the same amount at 10 pm. I fit lines with equal slope to both the A (10 pm) and B (10 am) treatments, as the graph shows. The two lines had different intercepts, p < .05. Although 10 am produces better balance, it produces worse sleep — more evidence that the sleep improvement and the balance improvement are due to different mechanisms. I want both improvements, so I am going to split my dose — half in the morning, half in the evening.
Of course, the fact that time of day of flaxseed oil matters is more reason to think that presence/absence of flaxseed oil matters. It is very hard to explain these results in terms of expectations: I had no reason to expect one time to be better than the other.