The Importance of Sleep Timing - The Apeiron Life Perspective
- Elizabeth Bradley, MS
- Mar 9, 2022
- 6 min read
Updated: Jul 21, 2022
What it is:
Just as there is no “one-size-fits-all” sleep duration, we each have a slightly different sleep schedule. This stems, in part, from genes that drive when we’re most alert and energized. The timing varies from person to person, with some preferring an earlier schedule, while others get their best work done later in the day. However, behavior and environment also dramatically shape our sleep schedule.
Many of us use a morning alarm that wakes us up earlier than we would naturally. Wake time on workdays can contrast significantly with days off when we indulge in an extra hour or two in bed.
Similarly, many of us are awake later than we might otherwise be in a world void of electricity and obligations. Late-night socializing can feed into a phenomenon known as “social jet lag” that can impair sleep and health in the long term.
Optimizing our sleep schedule requires finding a happy medium that allows us to get the sleep we need while accommodating our busy lives. We can manipulate our sleep timing to some degree, but going beyond a certain point can negatively impact our health. We should strive to work with our body clock wherever possible rather than against it.
The Purported claims:
Adopting a sleep schedule that works in sync with our body clock can:
Improve focus
Prevent disease
Promote longevity
Support weight loss and maintenance
Reduce inflammation
Balance sleep stages
What the science says:
Every cell in the body exhibits a circadian rhythm, which is an oscillating change in activity over a 24-hour day. During the day, our metabolism is high to support the mental and physical activity our body must perform, from the liver to neurons in our brains.
At night, metabolism slows down, and the body prepares for resting and repairing the damage done during the day. Damage isn’t a bad thing. It’s an inevitable outcome of something as simple as breathing oxygen and subsequent oxidative stress, or moving our muscles, creating micro-tears. Sleep is an essential deep resting state to revive, strengthen and improve our health, ready to start the next day anew.
The various cells of our muscles and organs are controlled by a central clock, the suprachiasmatic nucleus (SCN), which is within the brain’s hypothalamus. The SCN tells the rest of the body whether to engage in daytime activities (go, do, metabolize) or nighttime activities (rest, repair, restore) using light cues from the environment. During the day, light enters the eye and is detected by the SCN. While the SCN does many things with this information, one of the most important is that it puts the brakes on melatonin secretion from the pineal gland, also found within the brain. At night, in the absence of light, these brakes are removed and melatonin secretion begins. Levels start to increase 1-2 hours before bedtime and reach a peak around 3am.
The hormone melatonin is a powerful antioxidant and induces sleepiness. We can support healthy melatonin production by paying attention to our light exposure across the 24-hour period.
Bright, natural light during the day. Ideally, within the first few hours of waking up.
Dim, orange-toned light during the evening.
Near-total darkness for sleeping.
Unlike nocturnal mammals, humans evolved to be mostly awake during the day and asleep at night. However, work and social obligations don’t always work synergistically with this. Nightshift work – which is arguably essential for how society operates – is now considered a probable carcinogen due to multiple studies linking it with cancer. Blunted melatonin secretion in nightshift workers may play a part in this. As an antioxidant, melatonin’s nighttime release from the pineal gland is essential for neutralizing oxidative stress that can cause DNA damage. Being awake at night may promote the onset of diseases such as:
Cancer
Cardiometabolic diseases
Mood disorders
Inflammation
Immune health compromisation
Some of this inflammation can come from eating at night. Our ability to tolerate glucose and produce insulin appropriately is higher during the first part of the day. This declines steadily until the evening. Time-restricted eating with a fasting period overnight may be beneficial to most people’s health. Eating this way gives the digestive system rest and reduces inflammation, thus staving off disease and allowing for a higher quality of life.
The absolute time we go to bed or wake up in the morning is not uniform across all people, or even across the lifespan of any given individual. Children generally have an early body clock (chronotype), which means they are early to bed and early to rise. During the teenage years, the body clock shifts to a later schedule which often conflicts with early school start times. Once we enter adulthood, we migrate back to a slightly earlier chronotype, which shifts even earlier in old age.
In addition to these general trends across the lifespan, circadian clock genes housed within our cells determine our unique degree of “morningness”, or preference for being awake and productive in the morning. Some individuals do their best work early in the morning, others in the middle of the day, and others in the evening or at night. These different types of body clocks are sometimes called “early”, “middle”, and “evening” chronotypes, respectively.
In general, an early or middle chronotype is associated with better health. These chronotypes are most closely aligned with daylight hours. There is some debate over how much evening chronotypes are, in fact, under genetic control and how much this lifestyle is a consequence of modern-day electricity. Some studies have shown that when individuals with a later body clock are exposed to only natural light (such as in a wilderness camping setting), they shift to an earlier sleep schedule.
Our take:
When trying to improve your sleep, consistency is key. So too is paying attention to what your body needs. Going to bed when you first feel tired at night is one of the best ways to adopt a sleep schedule aligned with your unique chronotype. This sleepiness is an indication that melatonin is doing its job and the body is preparing for rest.
Powering through the first wave of sleepiness to watch another episode or finish a bit more work deprives the body of deep sleep which occurs during the first half of the night. Around 3 am, melatonin levels start to decline gradually, and our sleep cycles tend to trade from deep sleep to rapid eye movement (REM).
Both types of sleep are essential:
Deep sleep - rids the brain of metabolic waste products and repairs cell damage,
REM sleep - processes emotions and certain kinds of memory formation.
If we are operating on an extreme sleep schedule, such as very late to bed or very early to rise, we can deprive ourselves of either deep or REM sleep, respectively. We can cope with this occasionally, but it can be deleterious to health over the long term.
Will this benefit you?
Like any other routine, adopting a consistent sleep schedule is the best way of conditioning your brain and body to wind down in the time approaching bedtime each evening. Waking up at a similar time each morning also helps prevent an initial period of brain fog or grogginess which can sometimes occur on a highly varied schedule.
Balancing deep and REM sleep is essential for the health benefits associated with each kind of sleep and prevents a “rebound effect” after sleep deprivation. If we go to bed very late one night, the following night, our body will attempt to compensate for the deep sleep that was lost the night prior. Similarly, if we must wake up very early one morning, we will often have a REM rebound the following night. Bouncing back and forth in this way can leave us tired the next day, more inclined to reach for extra caffeine, and potentially find ourselves in a cycle of not being able to wind down at night when the time comes for sleep.
Still curious to try it? If you do, here’s what to keep an eye on:
If you wish to shift a consistently late bedtime earlier, it takes time. Focus on cultivating and supporting these new habits gradually.
Support healthy melatonin production by:
Getting adequate exposure to bright, natural light during the daytime. This is particularly important during the first half of the day and even the first hour upon waking.
By evening, switch from bright, overhead lights and blue-light emitting computer and phone screens to soft, orange-toned bulbs that are kept dim.
Many apps and proprietary settings are now included on mobile devices to work with our circadian rhythms and emit dim light and warm tones at night.
Another option is to use blue-light blocking glasses in the evening or ones with orange or red tints.
Pay attention to how you feel after spending a day out in nature, away from the desk. Are you tired earlier than usual? The combination of physical activity and natural light exposure often overrides any screen use at night. Our sensitivity to light at night intensifies after a day spent indoors, so remember to get outside as often as you can to reset your body clock. Your sleep will thank you for it.
References and additional resources:
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