@jamesduke209: SSRIs and SARIs have different mechanisms of action and side-effects. SSRIs are rarely used to assist with sleep issues while the latter, although not primarily prescribed for this purpose (depression being the primary) has been found to be effective at lower dosage. Trazodone is one such SARI that can help - at least on an occasional basis - due to the sedating effect it has. It does so by regulating serotonin levels and other brain receptors, including histamine - which OTC Benadryl, the generic name is diphenhydramine, also works to block.

I'm not entirely clear from your question, but if you're considering combining the two: 12.5 of diphenhydramine and 12.5 of Trazodone the short answer would be that's not advisable as it could lead to increased drowsiness and potential other interactions. BUT I'm inclined to think what you're asking is if you can try taking half the dosage of the 25 mg Trazodone. As long as it's a scored tablet you can readily halve, and not a timed-release capsule, that ought to be fine to try to see if it would have the desired effect. However, as with all medications and dosages,, your best bet, as @jc76 stated, is to confirm with the provider who prescribed it.

Hope it helps. Can you let me know if you get some good Zzzz's?