Waking up this morning was tough—as soon as I opened my eyes, Sleep threw a few lassos around my brain and tried to drag it back down. But someone requested I make her a cup of coffee and I dragged my ass into the kitchen, wondering about grogginess.

First, the word:

grog

1770 (implied in groggy "intoxicated"), supposedly an allusion to Old Grog, nickname of Edward Vernon (1684-1757), British admiral who wore a grogram (q.v.) cloak and who in August 1740 ordered his sailors' rum to be diluted. George Washington's older half-brother Lawrence served under Vernon in the Carribean and renamed the family's Hunting Creek Plantation in Virginia for him in 1740, calling it Mount Vernon.

So grogginess is named after the clothes of an admiral who wanted his sailors to be less drunk.

If you're groggy in the morning, Science calls that "sleep inertia": the perfect name. A little about sleep inertia:

Sleep inertia is a physiological state characterised by a decline in motor dexterity and a subjective feeling of grogginess, immediately following an abrupt awakening. Sleep inertia can also refer to the tendency of a person to want to return to sleeping. Typically, sleep inertia lasts up to 3 hours for a night wake up and up to 90 minutes for a day wake up. If the subject is awakened due to a perceived danger, however, the duration of sleep inertia is reduced to only a few seconds.

A study at the University of Colorado showed that people with sleep inertia are sometimes more impaired than people who are legally drunk.

Blame adenosine, a chemical compound that sticks to your receptors during wakefulness and non-REM sleep. Adenosine wants your body to sleep—its levels in your brain increase with every hour you're awake. It is used as a drug for people with supraventricular tachycardia (rapid heart rate). After being injected with adenosine, people report a "metallic taste" and a sense of "impending doom." Which doesn't sound very relaxing. Cells make adenosine as a byproduct of using energy. The harder they're working, the more adenosine they make, and the sleepier you feel.

Caffeine blocks adenosine receptors—that's its main job when it gets into the body, keeping those lassos from sticking.

• Jacque Davis

UPDATE!

According to Clothing of the Sixteenth Century grogram is "woolen cloth like grosgrain." According to the internet, grosgrain is a blog that is queasily enthusiastic about baby accessories.