I suppose lots of us start the day feeling a bit groggy: rather dazed, that is, and inclined to stagger about a bit.
Waking up isn't always easy!
It's all the fault of Admiral Edward Vernon. (Boo! Hiss!)
Edward Vernon was an admiral in the British Navy, and he really fancied himself. He wore a cloak of grogram, which is a mixture of silk and wool sometimes stiffened with gum.
Yes, it does sound a bit odd.
This cloak was such an mad thing to wear on a warship that the sailors called him Old Grog, which was short for old grogram.
Now, not only was Admiral Vernon a sharp dresser, but he was also MEAN. In 1740 he had his sailors' rum ration watered down. Now, rum was very important because, apart from the rum, more or less the only provisions the sailors got were weevil-infested biscuit and badly preserved beef.
The poor men called the watered-down rum grog, after Old Grog himself, and since then groggy has meant dazed from either tiredness, blows, drunkenness, or some idiot requiring you to get up in the mornings.
Thing Not To Do Today If At All Possible: be groggy.
Isn't it lovely that an attempt to stop sailors getting drunk should end up as a description of being tipsy?
And I think it serves Old Grog right!