Sleep

We primarily try to maintain or improve our health through proper nutrition, exercise, supplements, and, for some of us, green tea. However, we often overlook sleep as a crucial factor in our overall health. In fact, sleep is not only important, but it forms the foundation for good health. Neglecting sleep is like neglecting oxygen. It is so fundamental, yet it directly and fundamentally affects all our most important mechanisms, including metabolism, heart health, the immune system, brain function, and mental health.

Why do we sleep at night?

We feel drowsy when a substance called adenosine has naturally accumulated in our bodies. During the night, we build up a lot of adenosine from the hours we were awake, and that's how we go to sleep. The more proper sleep we've had, the less adenosine we'll have when we wake up. Of course, many of us have trouble falling asleep or staying asleep.

You may have already heard the term circadian rhythm. A circadian rhythm is our natural internal clock for regulating sleep and wakefulness. It is based on a 24-hour cycle (from the Latin circa, meaning "around" or "approximately," and diem, meaning "day"). Circadian rhythms occur in plants and animals, as well as in humans. For humans, when external factors disrupt our circadian rhythm by interfering with our sleep-wake cycles (e.g., by pulling an all-nighter, jet lag, etc.), all other mechanisms in our body begin to malfunction and deteriorate. Sleep is the foundation of good health. But how do we sleep well?

Sleep & Sunlight

You've probably noticed that there are many supplements available these days that claim to help you sleep better. But the most effective force that properly and positively influences our circadian rhythm is also completely natural. It costs $0 and is readily available to most people right outside their front door: sunlight. How does it work?

We wake up in the morning because our adrenal glands release a hormone called cortisol, along with another hormone called epinephrine (adrenaline). This happens both when we wake up naturally and when we wake up. Cortisol is also released whenever we experience intense stress, but there's a healthy amount that should be released when we wake up in the morning. This is crucial. When this happens, your body plans to release another hormone that makes you sleepy, called melatonin, about 12-14 hours later. This rhythm of cortisol and melatonin release occurs constantly in us, regardless of what's going on; however, without sunlight at the right time each day, their release times begin to shift. Why is this important?

When sunlight reaches our eyes in the morning, our eyes perceive a specific type of light within it. Our eyes then transmit this information to the central station of our circadian rhythm, located in our brain. This central station is called the suprachiasmatic nucleus (SCN). The SCN communicates with every cell and organ in the body. Sunlight must be communicated to the SCN to properly time the release of cortisol (the wakefulness hormone) and melatonin (the sleep hormone). If this doesn't happen, and the release times are incorrect, a host of extremely negative effects begin to appear throughout the body: heart problems, metabolic issues, dementia, learning disabilities, depression, and more. Nighttime cortisol releases are strongly associated with depression and anxiety disorders. Early morning cortisol releases, which are far removed from evening melatonin releases, improve various aspects of health, such as blood pressure, mental health, and more.

What to do?

Part I: Within an hour of waking up in the morning, go outside for 2 to 20 minutes (or longer if you have the time) and simply look around. If you wake up in the morning and it's still dark outside, just do this sometime in the morning when the sun is still low. Note that for this purpose, sunlight through a window is dramatically less effective than direct sunlight. The duration, 2 to 20+ minutes, depends on how bright the day is (the brighter it is, the less time you need). Just wake up, put your phone and sunglasses aside, and go outside—or better yet, take a nice walk! Even on a cloudy day, this will provide enough sunlight, although you should stay outside a little longer on a cloudy day.

Part II: Repeat this at sunset.

After just a few days, you should notice an improvement in your sleep quality and sleep schedule, provided there are no other sources of disturbance.

Miscellaneous?

Interior lighting

A study by a biologist at Johns Hopkins University shows that most of the light reaching your eyes between 11 p.m. and 4 a.m. suppresses the release of dopamine, the chemical in your brain associated with pleasure. This inhibits learning and triggers many adverse mood effects. Replace your bright overhead lights at night with dimmer, red-based lights that are kept at a low temperature. Try to avoid looking at all devices for about an hour before bedtime, as they emit blue light, which disrupts sleep.

Food & Exercise

Our circadian rhythm dictates that each organ has its own peak functioning time throughout the day. Eating within an 8- to 11-hour window during daylight hours and avoiding irregular or late meals has been shown to be extremely beneficial for our metabolism, heart health, gut health, immune system, and even mental health. Our muscles are also best suited for activity in the late afternoon (although the best time to exercise can vary from person to person). Even without strenuous activity or drastically altering our diet, we reap the greatest benefits simply by eating and exercising normally during our optimal circadian hours and avoiding these activities at night when we are preparing for sleep.

temperature

We all have different temperature preferences, but studies show that the optimal temperature for a good night's sleep for adults is between 60 and 67 degrees Fahrenheit (up to 69 degrees for babies). This may be too cold for many people, so simply make sure the room is a bit cooler, even if you usually prefer a warmer room when you're awake. If it's too warm, your body has difficulty regulating its temperature, leading to fatigue. A higher core body temperature has been shown to result in reduced restorative sleep and is associated with difficulty returning to deep sleep, meaning you get less time for deep recovery.

Here is a great 16-minute presentation by Dr. Satchin Panda of the Salk Institute where he explains circadian rhythm and its effects on overall health.