One of the biggest obstacles people face when trying to achieve optimal health is the ability to get not just the right amount of sleep but also the right quality of sleep. In today’s world of late-night TV and artificial lights it’s easy to forget that for thousands of years we lived in sync with the light and dark cycles of day and night.
Our physiology is still the same as our ancient ancestors. Despite the availability of artificial, 24 hour, 365 days a year light, our bodies are still tuned to the natural rhythm of daily and seasonal light/dark cycles.
Our Natural Sleep/Wake Cycles
The cycles of light and dark that result from the movements of the sun affect nearly all living creatures. Whenever light stimulates your skin or eyes, regardless of the source, your brain and hormonal system thinks it’s daytime. In response to light, your hormonal system naturally releases cortisol.
Cortisol is an activating hormone that is released in response to stress, which light is being a form of electromagnetic stress. This activates the body and prepares it for movement, work and other physical tasks. As the sun rises, our cortisol levels also rise and peak between 6am and 9am. They then drop a little but remain high through the middle of the day. In the afternoon and early evening cortisol levels begin dropping as the sun goes down.
Decreasing cortisol levels allow the release of melatonin and increase the levels of growth and repair hormones. If we follow our natural sleep/wake cycles, we start winding down as the sun sets and should fall asleep about 10pm. Physical repair mostly take place when the body is asleep between 10pm and 2am. After 2am the immune and repair energies are more focused on mental repair, which lasts until we awaken.
Disrupted Sleep/Wake Cycles
The continual release of stress hormones like cortisol may be a great idea for someone who is facing a life or death situation, but you don’t want this response to be an everyday occurrence.
A brightly lit house, late night TV and working late into the evening will keep stress hormones high past sundown. Fluorescent lights, TV and computer screens flicker on and off between 60-120 cycles per second, which your brain can interprets as sunlight.
Since cortisol can take hours to clear from your blood stream, this will also prevent the normal release of melatonin, growth hormones and important immune factors, cutting into your immune system’s valuable repair time.
If you go to sleep after midnight you’ve already missed over two hours of your physical repair cycle, which should start around 10pm. People who constantly stay awake after midnight commonly have a list of nagging musculoskeletal injuries, an increased incidence of headaches, and even neurological disorders.
Factors That Can Disrupt Your Sleep/Wake Cycles
What do most people do for a pick-me-up when they are tired? Most people reach for something to eat or drink that is sweet or even smoke. Caffeine, sugar and tobacco are all stimulants, which excite your sympathetic nervous system (SNS). This triggers the release of cortisol (stress hormone). Cortisol tells your brain that it’s the start of the day and it’s time to get active.