Light & Sleep


"Not enough sleep makes you fat, hungry, impotent, hypertensive, and cancerous, with a bad heart." - T.S. Wiley, *Lights Out*

Okay, so this quote may be a bit extreme, but it certainly got your attention. Sleep is one of those things we tend to put off for any number of reasons. Working late, watching TV, or just screwing around before going to bed. Regardless of the reason, your lack of sleep may be hurting not only your progress in the gym, but also your overall health.

Sleeping, or lack thereof, can be responsible for a whole host of health issues including weight gain, sugar cravings, elevated cortisol, and depression. Sleep is the time when our body produces melatonin, one of the most potent antioxidants. Antioxidants are molecules that inhibit the oxidation of other molecules. Melatonin, along with other antioxidants, act to protect cells from damage. But more than that, we need melatonin to help put us to sleep. 

Light is very problematic when talking about sleep. With light exposure, melatonin is suppressed. The light and dark cycles that we experience everyday should, ideally, coincide with when we go to sleep and when we wake up. Now, that can't always happen, but we need to make great strides to have clear cut times when we're awake (and around light), and when we're going to sleep (and around low/no light). 

We are very sensitive to light; much more than you may be aware. It's not enough to wear a sleep mask to block out light that hits your eyes. It's light that hits your body, in general, that is an issue. A study was done to determine if light exposure to your body can affect sleep (1). The researchers took used a fiber-optic cable to illuminate a small quarter-sized patch on the back of each subject's knee. Outside of that illuminated patch, the subjects were in complete darkness. This affected the subjects' temperature and melatonin secretion. Imagine what a bright TV screen would do?

These light and dark cycles control insulin through carbohydrate cravings and stress mechanisms. When the lights are on, your cortisol stays up because it's a blood-sugar mobilizer - it helps you to be ready to run or fight. If you continue this, and levels of cortisol stay high, cortisol, which mobilizes blood sugar, keeps insulin high leading to insulin resistance. 

As we now have been getting to winter, here are some general guidelines to mitigate some of these issues with the days getting shorter:

  •  turn the TV off 45-60 minutes before bed
  •  get up as close to dawn as possible
  •  after dark, keep the lights as dim as possible
  •  keep your bedroom as dark as possible (ZERO light)



1. Campbell, S. & Murphy, P. (1998). Extraocular circadian phototransduction in humans. Science, 279(5349), 396-399.

2. Wiley, T. & Formby, B. (2000). *Lights Out*. New York: Simon & Schuster