But being able to fall asleep so fast can actually be a symptom of asleep disorder.
This article explains the science of getting sleepy.
It also discusses sleep disorders that could leave you feeling sleepy throughout the day.
Illustration by Brianna Gilmartin for Verywell Health
Illustration by Brianna Gilmartin for Verywell Health
How Does Sleepiness Occur?
First, it’s important to understand how we become sleepy.
How Long Should It Take To Fall Asleep?
If it takes longer than 20 to 30 minutes, it could be a sign ofinsomnia.
But falling asleep in less than five minutes could signal an unhealthy level of sleepiness, too.
These brain waves are calledtheta activity.
These sleep-related brain changes are measured by tracking the electrical activity of the brain.
Sleep specialists use anelectroencephalogram(EEG) as part of a sleep study, called apolysomnogram.
Yourlong-term memorymay not keep track of the time you spend dozing off.
In most cases, though, there is a contributing factor or condition.
Sleep Deprivation
The most common cause of sleepiness issleep deprivation.
Most people need about seven or more hours of sleep.Some people mayneed more or less.
A little extra sleep may be all it takes to ease your sleep debt.
Waking up a lot is called sleep fragmentation.Your sleep is literally broken up.A common cause issleep apnea.
In people with sleep apnea, breathing stops briefly many times during the night.
These breathing problems can wake you up.
Fortunately, effectivetreatmentsexist to restore sleep quality.
Other Sleep Disorders
Other disorders can fragment sleep as well.
One possibility isrestless legs syndrome.
It causes an uncomfortable feeling that you better move your legs.Narcolepsyis another possibility.
This sleep disorder causes you to slip into sleep without warning during waking hours.
That’s the medical term for excessive sleepiness with no known cause.
The connection may be more established in people withhyperthyroidism(excessive thyroid function) who have trouble falling asleep.
For some people, it’s just a part of their makeup, while others may need help.
Check with a healthcare provider if you have concerns.
Testing
The simplest way to measure sleepiness is by completing a questionnaire called theEpworth sleepiness scale.
If you score higher than 10 on this scale, you probably have excessive sleepiness.
The next step may be a formal sleep study.
Themultiple sleep latency test (MSLT)can also be used to measure sleepiness.
It is sometimes used to check fornarcolepsy, and often follows a formal sleep study.
Sleep specialists record when your rapid eye movement (REM) sleep starts during a nap.
They also may point to an underlying health condition, like a thyroid disorder that requires diagnosis and treatment.
Summary
Feeling sleepy is the result of the chemical adenosine.
It builds up in your brain while you’re awake.
Sleep resets the adenosine levels.
Frequently Asked Questions
Some people sleep 10 or more hours at a time.
“Long sleepers” may be at risk for obesity, diabetes, high blood pressure, and depression.
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