An important lifestyle step to master is maximizing the rest and repair processes that are accomplished through adequate sleep. Although we have in many ways separated ourselves from dependence on the natural world, we are still physiologically linked to nature.
Our link to nature is clearly seen in our sleep patterns and in our hormonal system. Our hormones are intimately linked to several natural rhythms or biological clocks. These biological rhythms are based on the twenty-four hour cycle of daylight and darkness as well as the monthly cycle of the moon.
TWENTY-FOUR HOUR ADRENAL HORMONE CYCLE
Just like the monthly biological clock in females, both men and women, have twenty-four hour cycles, or daily clocks. While fluctuations in female hormone production vary with a monthly cycle, the adrenal hormone cortisol varies with a twenty-four hour or daily cycle. Cortisol levels peak in the early morning hours as the sun rises and taper off as the sun sets, reaching their lowest levels three hours after dark. This daily rhythm of cortisol dictates when we should be our most active and when we should rest.
Any time you fly and change time zones, the importance of this twenty-four hour biological clock becomes clear. Even a time change of a few hours can be enough to throw off one’s normal sleep cycle. Cortisol not only dictates our sleep and wake states; it is also the primary hormone involved in directing immune system functioning.
IMMUNE TRAFFICKING CYCLE
Have you ever wondered why your cold or flu symptoms get worse at night? It’s because the twenty-four hour rhythm of cortisol production regulates your immune system as well. As cortisol drops at night, our immune cells become more active. These cells leave the bone marrow and spleen to protect you while you rest. During this highly active period of immune function, immune cells kill bacteria and viruses. This basic immune activity relies on appropriate levels of cortisol. As cortisol drops at night, our immune system activity picks up, killing bacteria and viruses in large numbers leading to greater mucous production. This leads to more congestion and coughing at night as your body attempts to get rid of the mucous created from destroying bacteria and viruses. At daybreak, cortisol rises and immune cells return to the bone marrow and spleen to rest and recondition in preparation for the next nightly cycle.
NATURAL SLEEP CYCLE
If cortisol is out of balance, this normal immune function is compromised. As mentioned earlier, cortisol levels rise at daybreak giving us the energy to begin the working day. As cortisol drops naturally at night, we enter into rest and recovery, physical repair and psychic regeneration. Our immune system functions optimally if we to go to sleep by 10 p.m. As we sleep, physical repair takes place, immune cells patrol our bodies, eliminating cancer cells, bacteria, viruses and other harmful agents. However, if cortisol is elevated at night this immune function is compromised. If cortisol levels are normal during sleep, then true rest and recovery takes place thereby enhancing physical repair and immunity.
During sleep we also enter into stages of psychic regeneration. During these times, the brain releases chemicals that enhance our immune system. All during the night, we are going into Rapid Eye Movement (or REM) sleep states and non-REM sleep, alternating between light sleep and deep dream states. This is how we process the mental and emotional events of the previous day and refresh our minds for the day ahead. Most people need seven to eight hours of sleep to accomplish all these tasks. Without sufficient sleep, the immune system is hard pressed to keep up with its repair work and this creates the opportunity for disease processes to begin. If you miss out on proper rest, your physical repair and psychic regeneration will be compromised.