I'm confused

We have Horlicks in the house, which as I'm sure everyone knows is a malt drink you make with milk which helps you have a nice sleep.

Dad bought some Ovaltine the other day which is a malt drink that you make with milk which gives you energy and "helps you cope with today's hectic lifestyle".

They both have the same ingredients apart from Ovaltine having cocoa in it.

So if they are both essentially the same, how come one helps you sleep and the other one keeps you awake!!!????????????

Dad couldn't sleep at all the other night and he's convinced it was because he had Ovaltine before he went to bed.