Sleep, Rest, and Recovery

Two factors primarily control our sleep: the circadian rhythm and sleep pressure.

We have a biological clock in the brain that governs the circadian rhythm in cycles of about 24 hours. Cellular activity and our metabolism are also controlled by the circadian rhythm. We are programmed to be awake during the day and sleep at night, and metabolism increases during the daytime. Individual variations naturally exist, as some people are tired in the evening and alert in the morning, and others the opposite, with most falling somewhere in between. The circadian rhythm is controlled by light and darkness, and the hormone melatonin is released as it gets dark, making us tired.

Sleep pressure is controlled by adenosine, a molecule that functions, among other things, as a neurotransmitter. Adenosine accumulates in the brain during waking hours; the longer we have been awake, the more adenosine and the higher the sleep pressure, creating a stronger need for sleep. Taking a nap during the day reduces sleep pressure. To avoid disrupting night sleep, a nap should be no longer than 20 minutes.

The circadian rhythm and sleep pressure are two separate systems that must be synchronized, and they collaborate to produce tiredness. Adenosine can be blocked by substances like caffeine, which makes us feel temporarily more alert even if sleep pressure is high; we have high sleep pressure but don't feel it.

Why are sleep, rest, and recovery important?

When we sleep, the body cleans up after the day's activities. It processes and sorts impressions, emotions, and memories, and tries to merge old memories with new impressions. Old, broken, poorly functioning cells and organelles are cleared away, either to be discarded completely or to be recycled. Waste and byproducts from metabolism are cleared out. The body repairs and produces new material; in other words, it tries, as best it can, to heal itself.

Sleep can be divided into different phases, where we sleep with varying depth, which recur in 4-6 cycles during the night. Each cycle is about 1.5 hours. Besides the initial sleep onset phase, sleep consists of so-called standard sleep where we sleep "lighter" and are easily awakened, deep sleep, and REM sleep (dream sleep).

During standard sleep, which constitutes about 50% of sleep time, the brain sorts all the impressions we've received during the day. Short-term memory is cleared, and what is deemed important is stored in long-term memory, while other unimportant things are discarded. Too few hours of sleep in this phase makes it difficult to learn new things the next day because the short-term memory hasn't had time to be cleared. It also becomes difficult to remember things.

The deep sleep phase lasts 15-30 minutes per cycle and is longest during the first cycles. Here, we are difficult to wake, and this is where the greatest recovery occurs, with memory consolidation, cleaning, and repair. After about 4 hours of sleep, we have met most of our deep sleep needs. Getting enough deep sleep thus provides good quality sleep.

REM sleep becomes progressively longer in the final cycles, and everyone has likely woken up in the early morning from an unpleasant or pleasant dream, just before the alarm clock rings. In this phase, the processing of emotions, mood, creativity, and the linking of old memories with new impressions occurs. If one is under the influence of alcohol or drugs, REM sleep is suppressed.

All phases are therefore important for good quality sleep. If we don't give ourselves enough time and the right conditions for good sleep, we also don't give the body the conditions to heal from the day's activities and wear and tear, both physically and mentally.

It's not just the length of sleep that determines how much recovery we get; the amount of deep sleep can be more significant. If we sleep poorly one night with a lack of deep sleep, we can make up for it with more deep sleep the following night.

How does my sleep affect my health?

We all know it's important to get enough sleep to feel well and recover, to perform as well as possible during our waking hours. Yet, most of us probably sleep too little and not with good quality. Many are stressed, wound up, have difficulty falling asleep, and feel we don't "have time" to sleep.

Sufficient and good quality sleep is a crucial cornerstone of good health. All the important recovery processes that occur during sleep are vital for us to stay healthy, both physically and mentally. The section above on the different phases of sleep shows how important sufficiently long and undisturbed sleep is for the body's ability to recover and heal.

What happens if I don't get enough sleep?

As mentioned above, we can compensate for a temporary sleep deficit for a few days by accumulating a greater need for deep sleep. But too many days of poor sleep will eventually lead to significant health problems. The body doesn't get the opportunity to recover from the day's wear and tear, consolidate memories and process impressions, remove waste and debris, and to repair and heal.

The body will suffer from increased oxidative stress, which accelerates aging and damages cells, organelles, DNA, fascia, and more.

Health problems that can arise include memory problems, difficulty concentrating, behavioral changes, mood swings, a weakened immune system, high blood pressure, diabetes, obesity, cardiovascular diseases, digestive problems, stress (which can be both a cause and an effect), cancer, and more.

Sleep deprivation also makes us more and more stressed, with increased cortisol levels in the blood. The sympathetic nervous system is overactivated, and we have difficulty activating the parasympathetic system—the "rest and digest" state—which is required for good healing ability, digestion, and good health.

How do I get started with sleeping enough?

Two factors primarily control our sleep: the circadian rhythm and sleep pressure.

We have a biological clock in the brain that governs the circadian rhythm in cycles of about 24 hours. Cellular activity and our metabolism are also controlled by the circadian rhythm. We are programmed to be awake during the day and sleep at night. Individual variations naturally exist, as some people are tired in the evening and alert in the morning, and others the opposite, with most falling somewhere in between. The circadian rhythm is controlled by light and darkness, and the hormone melatonin is released as it gets dark, making us tired.

Sleep pressure is controlled by adenosine, a molecule that functions, among other things, as a neurotransmitter. Adenosine accumulates in the brain during waking hours; the longer we have been awake, the more adenosine and the higher the sleep pressure, creating a stronger need for sleep. The circadian rhythm and sleep pressure are two separate systems that collaborate to produce tiredness.

The sleep hormone melatonin makes us tired and helps us fall asleep and stay asleep. Melatonin is produced in the brain and secreted when it is dark, starting in the evening and peaking at night. When light enters our eyes, secretion stops.

But melatonin production is initiated early in the day by the light we get in our eyes in the morning; most important is the infrared light during the morning and early forenoon. It is therefore important to be outside during the day (preferably the first half) and get "daylight exposure" so that melatonin can be produced and then secreted into the blood when darkness falls.

If we expose ourselves to too much light in the evening, especially blue light from computers, TV screens, and so on, the circadian rhythm and melatonin secretion are disrupted. Therefore, it is important to dim all bright lights a few hours before bedtime. Blue light (most prevalent in the middle of the day) activates cortisol and wakefulness and inhibits melatonin secretion, making it harder to fall asleep.

It is also important to try to maintain regularity in your sleep pattern to sleep well. Finding your own rhythm and routine is important. For example, a cool bedroom can increase the likelihood of falling asleep. Calming down with breathing and relaxation exercises to activate the parasympathetic nervous system can also make it easier to fall asleep.

Also, avoid taking a nap during the day, at least not after lunch if you have trouble sleeping. It reduces sleep pressure and makes it harder for you to fall asleep. Try to endure, and eventually, the sleep pressure will become so great that you will hopefully fall asleep in the evening.

Coffee and tea block adenosine and reduce sleep pressure, so avoid them too late in the day.

Avoid coffee, sugar, alcohol, and tobacco, etc.

Avoid computers and mobile phones a couple of hours before bedtime

Try to avoid stress