Difference Between Sleep and Asleep

The term sleep is a noun or, in most cases, a verb that refers to the act of wanting to go to sleep. The term asleep is a verb that refers to the act of already sleeping, i.e., in a state of sleep. Both the terms sleep and asleep revolve around different aspects of the front of sleeping or falling asleep.

Sleep vs Asleep

The main difference between sleep and asleep is that sleep is a noun or a verb and asleep is an adverb or adjective. Scientists have been conducting experiments to find out what goes on while one is asleep. Similarly, the act of sleeping is mysterious and essential for the normal functioning of the human body.

Sleep Vs Asleep

Sleep could be considered a period when the body is inactive, and the mind and body are relaxing. The nervous system regains energy during this period of inactivity. The muscles are relaxed, there is no visible movement in the body, and the eyes are shut. The act of sleeping signifies that the body is incapable of any external movements.

Being asleep means, somebody is already sleeping. Dreams seep through when one is asleep. Most people are not alert when they are asleep. The body is in a state of passive consciousness. Asleep is necessarily the act when one is sleeping. It is not the act of going to sleep or getting up but essentially when one is sleeping.

Comparison Table Between Sleep and Asleep

Parameter of ComparisonSleepAsleep
Part of speechSleep can either be a noun or a verb.Asleep can either be an adverb or an adjective.
Past tenseThe past tense of the term sleep is slept.The past participle of the term asleep is was asleep.
RepresentationSleep refers to the act of sleep, which is the state of inactivity.Asleep refers to the condition of sleeping that is either continued or prolonged.
SignificanceSleep signifies the action of sleeping.Asleep signifies the state of sleeping.
Sentence usagePlease take proper sleep, or you will be dizzy.I thought you must be asleep.

What is Sleep

Sleep is what all animals, including humans, require for the proper functioning of their bodies. While some species thrive on less sleep, humans, in particular, need six to eight hours of sleep regularly. The neurotransmitters control the act of sleeping in the brain. Sleep may be easily disrupted or prolonged due to medicine, caffeinated drinks, pills, or supplements.

Usual habits may also affect sleeping habits. For instance, a smoker tends to have light and disrupted sleep. One important term associated with sleep is the Circadian Rhythms. These are characteristics changes that occur in your body during the course of the day. The biological clock of the body controls these rhythms. The reason why people feel sleepy and tired when it is dark is that the body stops producing melatonin, which is required to keep the body active.

The body’s clock controls melatonin production, body temperature, and any changes in the blood pressure levels. Until recent discovery, people thought that their body clocks sync in 24 hours. However, scientists recently found out that when light sources are taken away from the human body, the biological clock syncs every 25 hours. Due to the sunlight and artificial sources of light, your body coordinated from every 24 hours, one set at a time.

What is Asleep

Asleep refers to the act of sleeping. When one has their eyes shut and the body is seemingly passive, inactive, and deprived of movement, they are said to be asleep. Many people even say that death and asleep are only different due to one clause – a dead person does not wake up. There are certain stages when one is asleep. The most critical and mysterious part is called REM which is when one dreams.

Dreams are associated with the amount of your sleeping regime when you undergo the REM phase. REM starts about 90 minutes after you fall asleep. This is when your body shows changes. Your brain begins activity by sending mixed frequency signals to the brain. Your arms and legs become paralyzed, which prevents you from acting out of your dreams. Although most dreams come along during the REM stage of sleep, you can also dream in other stages while you are asleep.

These stages are non-REM and are called stages 1, 2, and 3. Stage 1 is your body’s way of converting from the state of being awake to the state of being asleep. Stage 2 is the period right before you enter deep sleep. Your muscles are relaxed and breathing controlled. Stage 3 is deep sleep and could be considered the most essential. Stage 3 sleep is what you require to feel fresh in the morning. The reason why most of your dreams are either early when you are asleep or towards the morning is that the REM stage is concentrated to early and late hours.

Main Differences Between Sleep and Asleep

  1. The primary difference between sleep and asleep is that sleep is essentially a noun while asleep is an adjective.
  2. While sleeping is a vital act required for proper functioning, being sound asleep (stage 3 sleep) is what imparts refreshment and energy.
  3. Sleeping is often associated with deep unconsciousness while being asleep also encompasses afternoon naps and the act of dozing off.
  4. Sleep is when the body is inactive, and the muscles are relaxed, while asleep is the act of already sleeping.
  5. Sleep is an old English word derived from the word ‘slaep,’ while the word asleep is a derivative of the word sleep.


As nuanced as the difference between the words sleep and asleep are, it is crucial to be aware of them. Sleep and sleep are often used interchangeably, and while it does not sound wrong, it is incorrect both factually and grammatically. Sleep and asleep also highlight the difference between the use and significance of noun and verb (sleep) and adverb and adjective(asleep). The sentence formation requires adequate attention to detail along with ensuring that the tense of the acting word is appropriate. Sleep is the most critical need of your body that you will have to cater to in order to be active, alert, and, more importantly, healthy.


  1. https://academic.oup.com/sleep/article-abstract/5/3/267/2753293
  2. https://go.gale.com/ps/i.do?id=GALE%7CA88571372&sid=googleScholar&v=2.1&it=r&linkaccess=abs&issn=00123692&p=AONE&sw=w

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