Barry and Irvine Fox in their book about using DLPA for pain and depression discuss using DLPA for a period and then taking a break. I think he says that some people take it for 3 weeks and then take a break for one week. You may consider doing this if you mean that you can take it for only a certain period and then have this problem again and again every time you try to supplement with it.

But most people usually experience some iritibility or anger issues from taking either DLPA or tyrosine consistently (without any breaks), not tiredness.

You might also consider taking DLPA instead since DLPA is essential while tyrosine is non-essential. I have to take DLPA because of pain issues I can develop with tyrosine. If DLPA causes the same problem then you know it is not tyrosine but it could be related to dopamine or catecholamines in general, perhaps.

Another possibility is that you may be low in iron. Iron is used in making dopamine from either of those amino acids. This you should check with your doctor though.

I developed lower back pain from supplementing DLPA and corrected that problem with an iron supplement.

How much of a dose are you taking and why are you taking it?

Of course I am not clear if you have this problem and stop taking it and then wait a period of time and start all over it again. Or, if you have the problem even after taking a short break.

But needing to cycle it would make sense if you experienced the irritability or anger problems normally associated with tyrosine. But needing to cycle it may also indicate that you are creating an imbalance with some other neurotransmitter. My experience is to take either 5htp or tyrptophan because the dopamergic systems needs to be balanced with the serotonergic system. But you may have some other imbalance going on instead. Serotonin is not usually considered for feelings of tiredness.

Also, are you tired, fatigued, lack motivation, or have low energy? Another possibility I think might be yawning all of the time. But, more details in your experience with feeling tired might help pinpoint the problem and the possible cause.