my suggestion is to ask your pdoc before using benadryl as a sleep aid. here's why:

What other drugs will affect Benadryl?

Do not take Benadryl if you have taken a monoamine oxidase inhibitor (MAOI) such as isocarboxazid (Marplan), phenelzine (Nardil), or tranylcypromine (Parnate) in the last 14 days. A very dangerous drug interaction could occur, leading to serious side effects.
Talk to your pharmacist before taking other over-the-counter cough, cold, allergy, or insomnia medications. These products may contain medicines similar to Benadryl, which could lead to an antihistamine overdose.

Before taking Benadryl, tell your doctor if you are taking any of the following medicines:

• anxiety or sleep medicines such as alprazolam (Xanax), diazepam (Valium), chlordiazepoxide (Librium), temazepam (Restoril), or triazolam (Halcion);
• medications for depression such as amitriptyline (Elavil), doxepin (Sinequan), nortriptyline (Pamelor), fluoxetine (Prozac), sertraline (Zoloft), or paroxetine (Paxil); or
• any other medications that make you feel drowsy, sleepy, or relaxed.

Drugs other than those listed here may also interact with Benadryl. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines, including vitamins, minerals, and herbal products.