My 8yr old autistic son takes vyvance 20mg. when it wears off he has an almost manic crash. would it be ok to give benadryl to offset the crash?

Vanishing vyvanse: What time does he experience the "wear-off"? If it is late in the day it would be difficult to introduce a "homework pill" - as it could compromise sleep. Vyvanse is available as 10 mg and it might not cute such a slump. It could be be that this is more unique to this product and other longer acting stimulants would be better tolerated. Focalin XR, dexedrine slow release, Concerta, Metadate