Circadian rhythm refers to the cycling of hormones according to the time of day. Every hormone cycles with daylight and darkness, each in it’s own way. Our brain has a master clock, called the circadian clock, controlled by specialized cells deep in the brain. There is a direct connection from our retina (in the back of the eyes) to the circadian clock in the brain. Blue light (part of the normal outdoor spectrum of light) stimulates very specific receptor cells in the retina which in turn communicates directly with the circadian clock telling the brain whether it is day or night. To synchronize our hormones and achieve restorative sleep, we must get outdoor light exposure to our eyes (without sunglasses, early in the day) and limit light exposure in the evening.
Artificial light, especially from cell phones and other devices that emit intense blue light, shift work, late night social activity, poor eating habits, sedentary lifestyle and at the opposite extreme, late evening workouts, can all disrupt our circadian rhythm preventing adequate restorative sleep. A rare genetic illness called fatal insomnia that strikes adults at middle age prevents sleep and results in death within a few months, highlighting the importance of sleep. Sleep deprivation can kill a human quicker than starvation! Adequate amounts of deep non-REM sleep are required for tissue regeneration, healing, DNA repair and immune function. REM sleep with dreaming provides great benefit by organizing our memory, discharging the emotional content of traumatic events, and facilitating creative brain activity. One night of short-sleep produces a state of inattention and slow reflexes as dangerous as driving under the influence of alcohol intoxication. Chronic short sleep and disrupted circadian rhythm results in increased risk of depression, cancer, hypertension, diabetes, dementia, obesity, metabolic syndrome, insulin resistance, heart attack and stroke, to name a few. Sleep interruption immediately halts weight loss during a calorie restricted diet (likely the result of hormonal disruption). So getting an adequate amount of restorative sleep every night is essential to good health. Here a few tips to help achieve a good night’s sleep each and every night.
- GET OUTDOOR LIGHT EXPOSURE ON YOUR EYES WITHOUT SUNGLASSES EVERY DAY, EARLY IN THE DAY. This helps set your biologic/circadian clock. Even on a cloudy day, outdoor light is much stronger and natural than indoor light. It is essential for setting your biologic/circadian clock. If you cannot get outside, stand or sit in front of a large window for 20-30 minutes in the morning, looking outside. Take a lunch break outside without sunglasses. Wear a shade hat instead of sunglasses. Your brain needs to experience natural outdoor light during the day.
- Avoid bright light in the evening, especially the light from TV, computer screens, cell phones, which all emit intense blue light and trick your brain into thinking it is daytime. Wear blue light blocking glasses/goggles for 2-3 hours before bed. (Amber tinted glasses which block blue light can be purchased on-line and can be worn over reading glasses) There is also software available that will decrease the blue light intensity of computer screens and cell phones in the evening.
- Practice time restricted eating. Limit all eating to an eight hour period, thus providing for an over-night fast of 16 hours. If that does not seem possible try to limit eating to a 10-hour period which provides a 14-hour overnight fast. This improves sleep, circadian rhythm, blood pressure, blood sugar and reduces stress hormones. NO SNACKS BETWEEN MEALS. NO FOOD FOR 2 HOURS BEFORE BED. For every hour decrease in eating time period from 12 hours to 8 hours you get health benefit.
- Eat an anti-inflammatory diet.
- If you snore, are overweight/obese, fall asleep during the day, or do not feel refreshed in the morning ask your doctor to order a sleep study. Obstructive Sleep Apnea makes restorative sleep impossible and increases risk of heart attack, stroke and most chronic diseases.
- Avoid alcohol altogether and avoid caffeine after late morning. Alcohol in the evening may help you fall asleep but it results in a withdrawal from alcohol during the night. This disrupts normal sleep patterns.
- Sleep in a cold, dark, quiet room. Use black-out curtains, no night lights, no phone charger lights, no lights of any kind should be on in the room. Any amount of light in the room impairs the production of melatonin which facilitates sleep onset.
- Have a wind–down time every evening. Develop habits of non-stressful activities, soft music, dim light, casual conversation, enjoyable reading. Do not spend evening time dealing with finances, conflict, or emotional activity.
- Try a magnesium supplement before bedtime. Magnesium glycinate, magnesium citrate, magnesium gluconate, are absorbed much better than cheaper supplements such as magnesium oxide. Magnesium L-Threonate is expensive, but it crosses the blood brain barrier into the brain with the greatest brain penetration of all magnesium supplements.
- Manage stress with yoga, meditation, regular exercise (but no intense exercise in the evening.) Perform most of your exercise outdoors in a green space. This provides much more health benefit than the equivalent exercise indoors.
- Regular contact with supportive family and friends is essential to health and reduces stress. The greatest predictor of health vs disease is the amount of social connectedness an individual experiences.
- Establish regular wake-up times and go-to-bed times. Regular sleep habits are essential. If you must rely on alarm clocks you do not have good sleep habits.
A few words about alcohol, caffeine and sleeping pills.
A drink or two in the evening may help you relax but it disrupts your sleep by causing a mild episode of alcohol withdrawal as your liver metabolizes the alcohol and your blood levels drop. Even this slight degree of alcohol withdrawal will impair a good night’s sleep.
Caffeine impairs sleep by blocking adenosine receptors in the brain. Adenosine is the neurotransmitter that increases gradually during the day creating a sate referred to as sleep pressure. Some people metabolize caffeine quickly, others slowly. The slower you metabolize caffeine the longer it takes to clear it from your adenosine receptors. Without adequate sleep pressure (adenosine receptors filled with adenosine in the brain) you cannot fall asleep. Many sleep experts recommend complete abstinence from caffeine and suggest that if you need caffeine to get started in the morning you are regularly sleep deprived.
Sleeping pills of all kinds interfere with normal sleep architecture. While they facilitate falling asleep, they impair your ability to achieve deep restorative stages of sleep and can produce many undesirable side effects including addiction, withdrawal symptoms, sleep walking, sleep driving, worsening of asthma and COPD, constipation, diarrhea, daytime drowsiness, burning and tingling sensations, unusual dreams, weakness, heartburn, etc…. Most importantly they all interfere with cycling through the various stages of sleep in a normal, restorative pattern!
If you want to explore these concepts in depth here are two excellent books that discuss sleep and circadian rhythm.
Why We Sleep, by Matthew Walker Ph.D.
The Circadian Code, by Satchin Panda Ph.D.
Eat clean, sleep well, spend time exercising out of doors, love one another.
Bob Hansen MD