I'm a morning person.

Did you know that people really do have biological rhythms which define us as morning people or night people? Neuroscientists have discovered some fascinating differences in how our brains are wired.

For one thing, night people apparently get stronger and more energetic as evening grows late. We morning people tend to hit our peak well before noon and then our energy and brain functions level off until drowsiness overtakes us just after the evening meal.

On the other hand, morning people are supposedly happier than night people! Who would have guessed that? I always suspected there was a party starting just as I was going to bed. That's apparently a large part of the problem for you owls. One study calls it "social jet lag," a disruption of circadian rhythms caused when you stay up late but are forced by responsibilities to get up early the next morning whether you want to or not.

(And by the way, your grumpiness really puts a damper on our bubbly morning effervescence. Try to keep it to yourself, okay?)

Here's one final scientific finding that supports everything we've long believed: the older we get almost all of us become morning people even if we were night people when we were younger.

Does this sound a bit suspicious to you? I believe the science but the more I read I keep coming back to a physical reality that circadian studies just don't seem to support.

I'm tired because I'm old. I wake up at four or five a.m. because I fell asleep in front of the TV ten hours ago.

Stick that in your MRI and smoke it.