A while back I mentioned an event that occurred when I was trying to go to sleep one night. Why don’t I let me describe it?

…a couple nights ago I was lying half asleep and heard a clicking sound of the sort that houses often make — the wood of the frame settling a bit or something. My mind said, “Oh, an annoying sound… whatever,” but my body had a noticeable reaction. I felt that feeling of “tinglies” traveling from my neck down to my body. I presume these “tinglies” to be adrenaline released to the body from the brain and I presume the individual “pricks of tingliness” to be this adrenaline stimulating the synapses of various muscle nerves.

I doubt this is uncommon and I suspect most of us experience it. I, personally, experience it more in the morning. I’ll be lying there, pleasantly adrift, and a thought or sound will occur that jostles me from sleep. As much as I would like to go back to my reverie, I can feel my body waking up, against my wishes.

I’ve long suspected that the reason for this must be something to do with hormone production. Basically, we go to sleep and our body spends the night replenishing spent chemicals (like adrenaline and glucocorticoids, which, while I don’t fully understand, are similar to adrenaline in function.) In the morning we’ve got a vast reserve of these chemicals and it doesn’t take much to get them to be fired off.

Recently I was reading an article on coffee and it hinted at the same idea. We shouldn’t drink coffee in the morning, it said, because our body is already rich with excitatory cortisol. (Cortisol is a glucocorticoid which is a type of hormone.)

…if we are drinking caffeine at a time when your cortisol concentration in the blood is at its peak, you probably should not be drinking it. This is because cortisol production is strongly related to your level of alertness and it just so happens that cortisol peaks for your 24-hour rhythm between 8 a.m. and 9 a.m. on average (Debono et al., 2009). Therefore, you are drinking caffeine at a time when you are already approaching your maximal level of alertness naturally.

This jibes with my sense that some excitatory hormone is at its peak during the morning. So I was pretty much right about everything, as usual.

I’m not going to stop drinking coffee in the morning though.