Sleep 101: Why You Might Not Wake Rested

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11 Nov Sleep 101: Why You Might Not Wake Rested

In this article, I’ll share how sleep works, discuss why many people suffer from sleep deprivation without knowing it and offer practical tips for getting better sleep and having more energy.

How Much Sleep Do You Need?

How much sleep do you really need? To answer that question, let’s consider an experiment University of Pennsylvania and Washington State University researchers conducted.

Here’s what happened:

The subjects who were allowed a full eight hours of sleep displayed no cognitive decreases, attention lapses or motor skill declines during the 14-day study.

Meanwhile, the groups who received four hours and six hours of sleep steadily declined with each passing day.

First, sleep debt is a cumulative issue.

In the words of the researchers, sleep debt “has a neurobiological cost which accumulates over time.”

If you get six hours of sleep per night for two weeks straight, your mental and physical performance declines to the same level as if you had stayed awake for 48 hours straight .

Second, participants didn’t notice their own performance declines.

We are poor judges of our own performance decreases even as we go through them. In the real world, well-lit office spaces, social conversations, caffeine and a variety of other factors can make you feel fully awake even though your actual performance is sub-optimal.

You might think your performance is staying the same even on low amounts of sleep, but it’s not. And even if you are happy with your sleep-deprived performance levels, you’re not performing optimally.

The Cost Of Sleep Deprivation

At what point does sleep debt start accumulating? When do performance declines start adding up? According to a wide range of studies, the tipping point is usually around the seven or seven and a half-hour mark.

Generally speaking, experts agree that 95 percent of adults need to sleep seven to nine hours each night to function optimally.

Most adults should be aiming for eight hours per night. Children, teenagers and older adults typically need even more.

How Sleep Works

A process called the sleep-wake cycle determines the quality of your sleep.

There are two important parts of the sleep-wake cycle:

  1. Slow-wave sleep (also known as deep sleep)
  2. REM sleep (REM stands for rapid eye movement)

During slow-wave sleep the body relaxes, breathing becomes more regular, blood pressure falls and the brain becomes less responsive to external stimuli, which makes it more difficult to wake up.

This phase is critical for renewal and repair of the body. During slow wave sleep, the pituitary gland releases growth hormone, which stimulates tissue growth and muscle repair.

Researchers also believe the body’s immune system is repaired during this stage. Slow-wave sleep is particularly critical if you’re an athlete.

REM sleep is to the mind what slow wave sleep is to the body. The brain is relatively quiet during most sleep phases, but during REM, your brain comes to life.

REM sleep is when your brain dreams and reorganizes information. During this phase, your brain clears out irrelevant information, boosts your memory by connecting the experiences of the last 24 hours to your previous experiences and facilitates learning and neural growth. Your body temperature rises, your blood pressure increases and your heart rate speeds up.

Typically, the REM phase occurs in short bursts, about three to five times per night.

If you starve yourself of sleep, you can’t recover physically, your immune system weakens and your brain becomes foggy. Or, as the researchers put it, sleep-deprived individuals experience increased risk of viral infections, weight gain, diabetes, high blood pressure, heart disease, mental illness and mortality.

To summarize: Slow wave sleep helps you recover physically while REM sleep helps you recover mentally. The amount of time you spend in these phases tends to decrease with age, which means the quality of your sleep and your body’s ability to recover also decrease with age.

Age-Related Sleep Changes

According to Harvard Medical School researchers, “As people age, it takes longer to fall asleep, a phenomenon called increased sleep latency. And sleep efficiency — the percentage of time spent asleep while in bed — decreases as well.”

There are many factors that impact the aging of body tissues and cells, but it stands to reason that if your body gets less slow-wave sleep to restore itself each night, the aging process will accelerate as a result.

How To Recover When You Don’t Get Enough Sleep

“At any age, most adults need seven and a half to eight hours of sleep to function at their best. Since older people often have trouble attaining this much sleep at night, they frequently supplement nighttime sleep with daytime naps.

“This can be a successful strategy for accumulating sufficient total sleep over a 24-hour period. However, if you find that you need a nap, it’s best to take one midday nap, rather than several brief ones scattered throughout the day and evening.” – Harvard Medical School

As it turns out, the body is incredibly adept at making up for a short-term lack of sleep. In fact, even if you got a brutal two or four hours of sleep last night, your body can usually recover fully if you get a solid nine or 10 hours of sleep tonight.

But, there is a limit on this recovery process, of course. Your body will do the best it can, but it will never be able to turn a deficit into a surplus. If you want to recover from a night of little sleep, you need to follow it with more sleep than usual.

The Circadian Rhythm

The circadian rhythm dictates your sleep-wake cycle. The circadian rhythm is a biological cycle of different processes that happen over a time span of about 24 hours.

Here are some key points in the typical 24-hour cycle (exact times vary):

– 6 am Cortisol levels increase to wake your brain and body

– 7 am Melatonin production stops

– 9 am Sex hormone production peaks

– 10 am Mental alertness levels peak

– 2:30 pm Best motor coordination

– 3:30 pm Fastest reaction time

– 5 pm Greatest cardiovascular efficiency and muscle strength

– 7 pm Highest blood pressure and body temperature

– 9 pm Melatonin production begins to prepare the body for sleep

– 10 pm Bowel movements suppressed as the body quiets down

– 2 am Deepest sleep

– 4 am Lowest body temperature

How To Sleep Better

Now that we understand how sleep works, let’s talk about some practical strategies for getting better sleep.

Avoid caffeine

If you’re having trouble falling asleep, eliminating caffeine from your diet is a quick win. If you can’t go without your morning cup of coffee, then a good rule of thumb to keep in mind is “No coffee after noon.” This gives caffeine enough time to wear off before bedtime.

Stop smoking or chewing tobacco

Tobacco use has been linked to a long line of health issues and poor sleep is another one on the list.

Use the bedroom for sleep and sex only

Is your bedroom designed to promote good sleep? The ideal sleeping environment is dark, cool and quiet. Don’t make your bedroom a multi-purpose room. Eliminate TVs, laptops, electronics and clutter. When you go to the bedroom, go there to sleep.

Natural Sleep Aids


There are too many benefits to exercise to list them all here. When it comes to sleep, exercise will make it easier for your brain and body to power down at night.

Furthermore, obesity can wreck havoc on your sleep patterns. The role of exercise only becomes more important with age. Fit middle-aged adults sleep significantly better than their overweight peers.

One caveat: avoid exercising two to three hours before bedtime, as the mental and physical stimulation can leave your nervous system feeling wired and make it difficult to calm down at night.


Most people sleep best in a cool room. The ideal range is usually between 18 to 21 degrees Celsius.


A quiet space is key for good sleep. If peace and quiet is hard to come by, try controlling the bedroom noise by creating “white noise” with a fan.


It is true that having a drink before bed often does help people fall asleep. However, while it makes it easier to fall asleep, it actually reduces the quality of your sleep and delays the REM cycle. Moreover, alcohol can spike insulin in the middle of the night and trigger waking.

How To Go To Sleep

Stick to a regular schedule

The body loves ritual. The entire circadian rhythm we laid out earlier is one big, daily routine. Go to bed and wake up around the same time each day.

Develop a “power down” ritual before bed

The light from computer screens, televisions and phones can hinder the production of melatonin, which means your body isn’t preparing the hormones it needs to enter the sleep phase.

Specifically, it is the blue wavelength of light that seems to decrease melatonin production. Developing a “power down” routine, where you shut off all electronics an hour or two before sleep, can be a big help.

Additionally, working late at night can keep your mind racing and your stress levels high, which also prevents the body from calming down for sleep.

Turn off the screens and read a book instead. It’s the perfect way to learn something useful and power down before bed.

Use relaxation techniques

Researchers believe that at least 50 percent of insomnia cases are emotional or stress-related. Find outlets to reduce your stress and you’ll often find that better sleep will come as a result.

Use strategic naps

Generally speaking, one nap in the early afternoon is the best way to add napping to your sleep cycle. This is particularly useful if you aren’t getting enough sleep each night as your body may be able to make up the deficit during your nap.

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