Everyone needs it.
Statistics show we are sleeping less, and everything indicates that this is bad for our health. At least 40 percent of Americans report occasional insomnia and some studies report that the number is as high as 70 percent. Twenty-four percent of us have difficulty sleeping every night or almost every night. There’s a higher incidence among women and the problem gets worse as we age. Although the exact function of sleep is still largely a mystery, some ingenious studies have given us a glimpse into the darkness.
Benefits of a good night’s sleep
During sleep we have greater heart rate variability. A heart rate of 60 beats per minute does not necessarily mean one beat per second. The interval between two beats may vary greatly from one beat to another. This beat-to-beat variability is a sign of health and a predictor of longevity. A steady one-beat-per-second rhythm usually suggests heart disease or some other serious condition, and it is a predictor of poor health.
Sleep promotes other healthy rhythms as well. When we’re sleeping soundly, some of our biological functions line up their rhythms with each other. These functions include our respiratory rate, blood pressure and brain waves. This same phenomenon happens when we’re in a state of meditation, feeling gratitude or appreciation, or “in the zone” that athletes describe when they feel they’re functioning at their best. Scientists call this rhythmic synchrony entrainment, and they agree it’s good for our health.
Entrainment and melatonin
Entrainment was first noticed and written about in the 17th century by Christian Huygens, a Dutch physicist who invented the pendulum clock. He noticed that if he placed two pendulum clocks next to each other on a wall and swung their pendulums at different rates, they would eventually end up swinging at the same rate. It was ultimately found that the heaviest pendulum pulled the other into its rhythm until they were synchronized.
Melatonin, a hormone secreted by the pineal gland in our brain when we’re in darkness, entrains our body rhythms with the day-night cycle. It’s a powerful antioxidant, helps in modulating our immune system and may discourage the growth of certain cancer cells. Proper melatonin levels affect sexual development and quality of sleep and overall play a role in slowing down the aging processes. The amount of melatonin released from the pineal gland is proportionate to the length of night. In this way, melatonin gives other body systems information about the time of day and time of year. Studies have shown that when we sleep in total darkness, we secrete more melatonin. Even a small amount of light hitting our closed eyelids drastically reduces the amount of melatonin released into our bodies. Only red light does not have this effect. When we sleep with light from a nightlight or even a crack through the window shades, our melatonin secretion plummets. Sadly, these days it can be hard to find a night’s sleep in total darkness; a picture taken from space of the modern world at night shows a sea of bright lights.
In addition to getting too much light exposure at night, most of us who live in industrialized countries do not get enough exposure to the right kind of light during the day. We’re exposed to artificial light rather than the full spectrum of natural light. This has been shown to cause seasonal affective disorder, a form of depression more common in the winter months. A robust secretion of melatonin depends on exposure both to natural light during the day and to darkness at night—the conditions of human life at its beginnings in the peri-equatorial African-Syrian Rift Valley. Our lifestyles may have changed, but for the most part our genetics have not. At times, our modern life puts us out of sync with some of the needs of our biological systems.
More benefits of sleep
During sleep we recover from the activities of wakefulness. Our bodies rebuild stores of molecules by replacing or repairing damaged molecules needed for the next day. When we’re deprived of sleep, the brain makes molecules that are ordinarily associated with stress—proteins that don’t fold properly and that clump together, and heat-shock proteins that are designed to help the body cope with stress. So if you sleep well, you have a tune-up overnight; and if you don’t sleep well, your system experiences cellular stress. Sleep also reduces inflammation and improves immune function. There has been speculation about other “off-line” functions performed by the brain during sleep, such as keeping memory tuned up and fit by exercising it with dreams, and refreshing circuits for new memories. Consequently, sleep is restorative, and a lack of sleep is associated with fatigue and cognitive impairment.
Research has shown that people who don’t sleep well, who work night shifts, or who have jet lag can develop health problems at a higher rate than those with regular sleep patterns. People also have difficulty losing weight if they’re not sleeping well.
How much sleep do we need?
The conventional wisdom is that we need seven or eight hours of sleep per night. Research shows that people living in industrialized countries who get this much sleep are healthier than those who get less. We should wake up feeling refreshed and have no daytime drowsiness.
How to get a good night’s sleep
Here are some habits that can help you get a good night’s sleep. Adopt a regular sleep time and develop a relaxing bedtime routine. During the hour or two before bed, do not consume large quantities of food or beverages, exercise vigorously or focus on aggravating issues. In addition, avoid using a computer or watching TV; the light from computer screens and TVs excites the brain. Keep your bedroom cool, dark and quiet. Go to bed tired and turn out the lights. Have a comfortable mattress and pillow. Sleep primarily at night, and limit daytime naps to a maximum of thirty minutes. Sleep in total darkness or use a sleep mask. Avoid nicotine and limit nighttime caffeine, alcohol and sugar consumption. All of these chemicals are stimulants. Nicotine is an outright stimulant, as is caffeine. Alcohol makes you drowsy at first, but then wakes you up a few hours later. Some people are more sensitive to these chemicals; and if you have any trouble sleeping, completely avoid them to reestablish a healthy sleep pattern.
Having trouble sleeping? Read MINDFUL SLEEP: Practice mindfulness to relieve insomnia>>