There’s a fascinating part of the brain called the Suprachiasmatic Nucleus (SCN). It’s very small and it’s located deep within the brain. The SCN is responsible for regulating our daily sleep-wake cycle, and the primary stimulus it responds to is sunlight.
Here’s how it works. Special receptors in the back of the eye detect bright light. The optic nerves carry this information from each eye to the visual cortex in the back of the brain, but halfway along these big nerves cross over each other, so information from the left visual field goes to the right side of the brain and vice versa. This is the optic chiasm (“chi” is the Greek letter X). This is where nerve fibers branch off and join the Suprachiasmatic (literally “above the X”) Nucleus, which is where the circadian rhythm is controlled.
As you probably know, our bodies have an internal clock that regulates various functions on a 24-hour cycle. The term Circadian Rhythm, from the Latin circa “around” and diem “day”. Sleep, physical activity, alertness, body temperature, digestion, and immune function all fluctuate on this daily cycle. The SCN coordinates all these rhythms across the whole body, but it all depends on exposure to light, especially sunlight.
One of the strategies to combat insomnia is to expose yourself to bright, natural light within the first hour of waking up. This helps reset your internal clock, so later that evening your body is ready to go to sleep. Without exposure to light, particularly the wavelengths produced by the sun, your sleep schedule can go awry. If someone lived in near-darkness all the time, their body would still follow a circadian rhythm, but basic physiologic functions (like sleep, energy levels, and digestion) could become grossly disordered if not synchronized by the SCN. Ironic that one of the best things you can do for sleep is get out in the sun!
How much more important is it to expose our hearts to spiritual light every day? How else will we experience God’s mercies “new every morning” (Lam 3:22-23)? Is there any other way to receive our daily bread than fixing our eyes on the Light of the world? It doesn’t matter if your time of personal devotion occurs in the morning, midday, or before you go to bed. However, incorporating time alone with the Lord regularly each day is crucial to our spiritual health.
Read the Bible every day. Make it a part of every day’s business to read and meditate on some portion of God’s Word. Private means of grace are just as needful every day for our souls as food and clothing are for our bodies. Yesterday’s meal will not feed the worker today, and today’s meal will not feed the worker tomorrow. Do as the Israelites did in the wilderness. Gather your manna fresh every morning. Choose your own periods and hours. Do not hurry your reading. Give your Bible the best and not the worst part of your time. But whatever plan you pursue, let it be a rule of your life to visit the throne of grace and the Bible every day.
J.C. Ryle, from “Practical Religion”
Relying on God has to begin all over again every day as if nothing had yet been done.
C. S. Lewis, from “Letters of C. S. Lewis”
Just like proper sleep starts with daily exposure to the sun, so too our spiritual rest starts with daily approaching the Son.
Come to me, all who are labor and are heavy laden, and I will give you rest. (Mt 11:28)
Blessed be the Lord, who daily bears us up; God is our salvation. (Ps 68:19)
In order to receive the Lord’s restoration, we must first come to the Light. Our brains need sunlight, and our hearts need Son-Light.
Every. Single. Day.