Thursday, May 31, 2012

Some Recurring Sleep Myths: Television versus Melatonin

When I discuss sleep issues with patients, specifically issues which may result in lest rested sleep, I frequently hear beliefs about sleep that are... well, just not true. I thought I would address a few common ones which frequently come up in conversation and explain them a bit.

1. Television before bed.

When I tell people that they should have a regular pre-sleep ritual before bed that does not include the television, such as reading 1 short story from a book collection/1 magazine article/1 newspaper article, they often tell me that watching TV is their ritual and they have to do it if they want to relax and fall asleep. That is actually just not true, if they are implying that it is the only thing that will or would work for them. It may be the only thing tried so far, or perhaps the easiest regular thing to do before bed, but not the best thing to do before bed. And it is often quite counterproductive.

I realize that studies suggest at least 80% of people (in America) keep a TV in the bedroom and at least 50% of people's dominant pre-bedtime activity is watching television. That makes it common... but common has no relationship to what is actually good for us.

Our brain and body have the great capacity to pick up new habits and rituals and we can easily replace TV with a book if desired. The reality for me as much as anyone else is that it is easier to watch TV passively than to actively read a book's short story, so we might gravitate to the easier-to-accomplish ritual.

But what's so wrong with TV? Well, it's not inherently bad; the timing is just all off. First of all, most TV shows are designed to at least hold your attention in 30 or 60 minute increments, so many people will drift off after they reach at least one "stopping point" which is the end of some segment of watching in one or most of these increments. The commercials are usually louder than the show, so they will continue to interrupt the person's sleep after they drift off, until the timer turns the TV off, the first restroom break, or all night. Ongoing flashing lights from the TV can have the same interrupting quality as well.

But the bold light of the late night TV/ipad/computer/laptop/iphone in your face up close is the frequent culprit. Long before we all lived in houses with artificial suns, we woke and slept to the sunrise and sunset. This was so long a part of our history that we have a special unconscious anatomic pathway for light, separate from the pathway for light that we respond to and this pathway even intact in most blind individuals. This is a whole different pathway for light that enters our pupil and hits our retina at the back of the eye. Instead of heading on to the back of our head (occipital lobe) to be interpreted as images, this pathway heads down on a smaller tract to a part of the brain called the hypothalamus, before communicating back a part of the brain called the pineal gland.

Now this is where it get's interesting:

The pineal gland is where melatonin is released, and melatonin is one important(of many) neurotransmitters that communicates to your brain that it is time to start orchestrating sleep.

Melatonin is chemical night.

It makes sense. You, as a conscious human, cannot consciously demand that your brain start orchestrating dozens of neurotransmitters into place to start negotiating sleep, just as I cannot consciously understand my desktop computer enough to demand the pixels to show me a picture of the melatonin molecule. But I can click on Google to search for it and let my computer work on its automatic, pre-programmed setup to show it to me. In the same way, the sun sets and the brain's automatic plans start, stimulated by melatonin at almost the same time each evening/night, to help you go to sleep.

So, what does this have to do with Television? It's an artificial sun, an... anti-night if you will. It shuts down the production of melatonin because that light pathway I spoke of above is not stimulated by darkness as it should be. Reading under moderate indirect light (like it's predecessor, campfire) does not inhibit melatonin's release.

So again, our sun, and our little mini-electronic suns (like the TV) suppress melatonin and therefore suppress sleep momentum. Nighttime (darkness), lets melatonin rise so the complex mechanisms can start pushing our brains into sleep. 

If you're watching television, you're telling the body the sun's still up, the day's still happening. This distorts our baseline circadian clock that we develop over days and weeks in our background, the clock that helps you wake without your alarm in the morning after awhile (if you're getting enough good sleep).

So, develop a better pre-sleep ritual strategy than TV. Your physiology will thank you for it.

In the most straight-forward way I know, I have summarized the extra pathway for light I mentioned above:

The Retinohypothamic Tract:

Hypothalamus (The suprachiasmatic nucleus to be specific)
Down into the Midbrain & Brainstem
Pineal Gland
Voila!.... Melatonin