For many people sleep is simply something you do at the end of each day and they don’t put much more thought into it. While sleep may seem mundane, it is actually a very interesting concept that is largely still a mystery to modern science. Questions like “why do we sleep?”, “how long can you go without sleep?”, and “why do we dream?” are all questions that have no solid answer even after decades of research.
While there is still a lot unknown, there are aspects of sleep that modern science has discovered and one of those is the concept of sleep debt. Sleep debt can be thought of in terms of a credit card bill. At the end of each day, you have a bill you need to pay with hours of sleep. If you sleep less than the amount you owe, that debt is then passed on to the next day.
Below is a closer look at the concept of sleep debt as well as other aspects of sleep. With nearly a third of our lives spent sleeping, it only would make sense to understand what your body is doing during this time and ways you can promote better sleep.
Stages of sleep
Sleep is a multistaged process that occurs in cycles every night. Light sleep stages represent when you are easily woken up and more closely resemble brain activity while awake. Deep sleep stages are harder to wake up from and have unique observable differences from a conscious individual.
During any night the body will cycle through stages of light sleep, deep sleep, and light sleep again. These stages of sleep can be further broken down into REM and non-REM sleep. Below is a breakdown of the two categorizations of sleep.
Non-REM sleep can be thought of as light stages of sleep. The non-REM sleep stands for non-Rapid Eye Movement Sleep. Rapid eye movements are indicative of deeper sleep and are a necessary component to providing quality sleep.
Non-REM sleep tends to increase with age and is a large reason that many people have difficulty staying asleep in mid to late adulthood. It is easy to be woken up during non-REM sleep. Because the body makes many sleep cycles in one evening of sleep, many people find that they wake up at a similar hour each night like 3 am for instance. The most likely reason for this is that 3 am happens to be when they are in lighter sleep stages and that there is some sort of external stimuli such as light or being uncomfortable that wakes them up.
REM sleep represents the deepest levels of sleep. During REM sleep your body is essentially paralyzed and brain waves become incredibly active and sometimes can resemble those of someone that is awake. During this sleep state, your eyes move continuously and rapidly.
REM sleep is often associated with the stage of sleep that dreams occur. On top of being the dream state, REM sleep is a vital component of sleep and many consider it to be the reason why we sleep. While the exact way REM sleep works is unknown, it is known that without REM sleep people can begin to develop signs of sleep deprivation
Everyone at some point has not gotten adequate sleep. Whether it be due to late-night studying or partying, the effect on the body is the same. With a lack of sleep typically comes a wave of fatigue the following day. This wave of fatigue can be thought of as the price you pay for not getting enough sleep.
One sleepless night however is not the end of the world, but how does the body compensate for lost sleep? Below is a closer look at the detailed mechanisms behind how your body pays off its sleep debt and what exactly the body needs from sleep.
Even though you have most likely had at least one instance of insufficient sleep, this doesn’t mean you will be tired and groggy the rest of your life. Instead, your body makes up for this lost sleep the following night.
The night following a sleepless night represents when your body makes up for lost sleep. During that specific night’s rest, you may sleep longer, or you may enter REM stages of sleep more frequently. The phenomenon that REM sleep increases following a sleepless night is known as REM rebound.
Because of REM rebound, an individual is able to have occasional bouts of sleeplessness without having a significant effect on your wellbeing or livelihood. Rather all that individual needs is to go to sleep the following day and everything is alright.
How long can you stay up?
The longest recorded amount of time without sleep occurred in 1963 by Randy Gardner. Gardner stayed up for 264 consecutive hours. While you most likely will never stay up for 11 days straight, it is nice to know what is possible for the human body.
While Gardner was able to stay awake for 264 hours, did it place undue stress on his body or did it have any lasting effects? Below is a closer look at what happened to the record holder.
The night after
The night that followed Gardner’s sleep deprivation proved to be quite interesting. One would think that after over a week without sleep that Gardner would need at least half of that time to recover, but in the case of Gardner’s 264-hour record, he simply slept for 14 hours and was good as new.
The comparatively short amount of time for recovery illustrates that REM sleep is what matters, not just length. During those 14 hours, Gardner was most likely in REM sleep more frequently as his body tries to play catch up.
This intuitively makes sense in some ways. When you have had poor sleep the night before and then go to sleep, you are likely to fall asleep hard and not remember falling asleep or tossing and turning in the night. This is because you are attaining more REM sleep and your body during these stages is essentially paralyzed.
Surprisingly after 11 continuous days of being awake, Gardner experienced little to no lasting effects. As Gardner got older, however, he did develop insomnia. Whether or not his 11-day stunt was to blame is unknown but the fact that he had little to no lasting effects illustrates how the body is effective in catching up on lost sleep.
One sleepless night has little effect on you long term and in the case of Gardner, apparently, 11 continuous sleepless nights also has little effect on your long-term health. With Gardner’s experience, you can rest assured knowing that your body is immensely capable of catching up on lost sleep.
How to Get Better Sleep
While a late-night occasionally is nothing to worry about, a continual lack of quality sleep can put your health at risk. An increased chance of developing heart disease, high blood pressure, diabetes, obesity, anxiety, and depression can occur as a result of chronic sleep deprivation.
With sleep deprivation, your body is constantly trying to make up for lost sleep, but each night it is unable to attain a good enough quality of sleep to properly recoup. People experiencing difficulty with sleep are oftentimes run down, groggy, and not able to cognitively perform to the best of their abilities.
To get your sleep in order there are some simple habits you can create to help support more restful sleep. Below are a few of those habits.
A large contributing factor to the quality of sleep you get is your circadian rhythm. The circadian rhythm is your body’s internal clock that regulates changes in your body every 24 hours. Sleep is an integral part of the circadian rhythm and utilizing your body’s natural mechanisms to your advantage is ideal.
The best way to train your circadian rhythm is to stay consistent with your wake-up and bedtime, even on Friday, Saturday, and Sunday. Staying consistent essentially trains your body to start expecting to wake up or go to sleep which can allow for an easier time going to sleep and waking up.
In fact, a well-adjusted circadian rhythm can act like an internal alarm clock that wakes you up at the same time every day and allows you to be more productive in the morning. When your body knows approximately when it is time to wake up it will begin taking you out of deeper sleep stages and will transition you into lighter and lighter sleep stages. When you wake up from light sleep you are more likely to feel well-rested than being awoken from a deep sleep.
Your sleep environment is incredibly important as sounds, light, and other stimuli such as an uncomfortable mattress can cause you to wake up in the middle of the night. During sleep your body cycles through deep and light sleep stages. If you are in a light sleep stage and have an external disturbance you are likely to wake up.
Creating a dark, quiet, and comfortable environment through the use of blackout curtains, eye masks, earplugs, and a comfortable mattress can support better sleep.
In summary, the human body is incredibly well adapted to ensuring it gets the sleep it needs to function optimally. With REM rebound the body is able to make up for lost sleep and restore your alertness and wakefulness the following night.