When you think of a sleeping disorder, you may think more about individuals who have trouble falling asleep. This is known as insomnia. However, if you fall asleep too quickly, that may also be a sign of an underlying sleep disorder.
Falling asleep too fast is normally characterized as being able to fall asleep anywhere, or nodding off almost immediately after laying down. Continue reading to learn more about sleepiness, and what may be some indications for you to speak to your health professional about your symptoms.
How Sleepiness Occurs
The first thing to understand is how sleepiness occurs. When you wake up, your brain produces a chemical called adenosine. It needs energy to wake up the rest of your body functions and get going for the day. Adenosine gradually rises throughout the day the longer that we are awake.
High levels of adenosine can create the homeostatic sleep drive, which is also known as sleep load. It is essentially the physical need for sleep to restore your body. For example, if you were awake for 30 straight hours, then you would feel much more sleepy than if you had just been awake for four hours. Therefore, you may feel the need to just drop into bed because your sleep load is so high.
Other behaviors can impact your adenosine levels, like staying up later than normal, or waking up earlier than you usually do. Therefore, when it's time to go to sleep, you may fall asleep faster than normal because your sleep load is so high.
When you are asleep, the lymphatic system, which is like a "sewage clean up" in your body, clears the levels of adenosine from your brain. So, the levels of adenosine are the lowest in the morning, as is your sleepiness (because of a low sleep load). But what happens when these levels are consistently too high?
How fast is too fast for falling sleep?
Because you're in the process of falling asleep, you may not actually know how long you take to fall asleep. Your long-term memory may not be able to keep track of how much time you spend dozing off. Therefore, you may feel like you're falling asleep faster than you actually are.
Additionally, the lightest stage of sleep can feel like wakefulness if you suddenly wake from it. Therefore, you may feel like you were awake longer than you were because you were slipping in an out of light sleep.
You are considered asleep when your muscle tone relaxes, and the electrical waves in your brain begin to slow down. This is why the stages of sleep are associated with different waves on an electroencephalogram (EEG). Delta waves are the longest and slowest waves, indicating that you are in deep sleep. That is when it's hardest to wake you up, but your body is doing the most repair and recharging.
The time it takes for you to transition from wakefulness to sleep is called sleep onset latency. It is measured by the electrical activity of your brain. EEGs can detect this transition through small electrodes placed on your head that monitor your movement from wave to wave. The average person that does not have excessive sleepiness should fall asleep from 5-15 minutes. If this stage lasts longer than 20-30 minutes, it could be a sign of insomnia.
Falling asleep in less than five minutes may not necessarily indicate that you are just that great of a sleeper. Instead, it may be a sign of sleep deprivation, or an underlying sleep disorder that affects sleep latency.
Causes of excessive sleepiness
The most common cause of sleepiness is sleep deprivation. Without enough hours to feel rested, you won't clear away the adenosine from the previous day(s). The recommendation for adults is 7-9 hours of sleep. Persistently getting less than this will increase your sleep debt, thus increasing your sleep load. If you fall asleep quickly, take naps, doze off unintentionally, sleep in on days off, then you may be a bit sleep deprived. A little extra sleep may relieve temporary sleepiness, but it can't erase all of your sleep debt.
If you're not getting quality sleep, or toss and turn all night long, then you also are not clearing away all of the adenosine. Waking up frequently throughout the night is called sleep fragmentation. Too many nights of this can cause you to fall asleep quickly. One example of this is sleep apnea, which consists of the inability to breathe throughout the night due to an airway blockage, causing the body to wake up to begin breathing again.
Other sleep disorders that can cause fragmented sleep include restless legs syndrome and periodic limb movement disorder. Both of these are described as persistent movement throughout the night, but their causes differ. Restless legs syndrome can be described as a tingling or stinging feeling that is only relieved by movement. Period limb movement disorder are simply repetitive movements throughout the night, similar to a type of focal seizure.
Narcolepsy is another cause of falling asleep fast. Narcolepsy is a sleep disorder where you have irresistible urge to fall asleep, and can even be associated with cataplexy, or sudden loss in muscle tone. Some types of narcolepsy have episodes triggered by intense emotions. Usually these individuals sleep right into rapid eye movement (REM) stage, which is normally the last stage of sleep that you should enter. This can be diagnosed with a sleep study, or polysomnograph.
And last, but not least, you may just be a very sleep person, which is called idiopathic hypersomnia. It's a diagnosis of exclusion when they can't find anything else that could be causing your abrupt sleepiness.
Diagnosing
Diagnosing why you are so sleepy can be done in a couple of ways. One is by completing a questionnaire called the Epworth sleepiness scale. If you score higher than 10, then more likely, you have excessive sleepiness. After this screening questionnaire, you may move on to a sleep study.
The multiple sleep latency test (MSLT) can measure sleepiness. It is used to check for narcolepsy, and you're given the chance to take 20-minute naps every two hours during a day. Falling asleep in less than eight minutes is considered abnormal, and scientists will measure when your brain enters REM. If REM starts within 15 minutes in two or more of your naps, then you'll be diagnosed with narcolepsy.
If you think that you fall asleep very fast and at inappropriate times, then please click the orange button to take a free online sleep test and talk with one of our sleep health professionals.
https://www.verywellhealth.com/could-falling-asleep-too-fast-be-a-sleep-problem-3015146