Falling Asleep Randomly: It’s Not Always Narcolepsy

Falling asleep randomly can be due to sleep debt, circadian misalignment, narcolepsy, sleep apnea, alcohol, depression, or medical conditions like diabetes.
Updated
2023-10-11
16 MINS
Written by
Jeff Kahn, M.S., Rise Science Co-Founder
Reviewed by
Chester Wu, MD, Rise Science Medical Reviewer
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What Causes You to Fall Asleep Randomly?

  • The two most likely causes of falling asleep randomly are high sleep debt or being out of sync with your circadian rhythm. 
  • Falling asleep randomly could also be caused by narcolepsy, sleep apnea, alcohol, anxiety, depression, poor sleep hygiene, or medical conditions. 
  • The RISE app can help you lower your sleep debt and get in sync with your circadian rhythm to stop falling asleep during the day and give you more energy.

At your desk, behind the wheel, during an anniversary dinner with your spouse — there are times in life when you really don’t want to fall asleep. But even if you’re just sitting in front of the TV, it can be worrying to find yourself falling asleep all the time. 

Below, we’ve rounded the 12 reasons you might be falling asleep randomly and covered how the RISE app can help you with the two most common: sleep debt and circadian misalignment.

Ask a Sleep Doctor

Before we dive into why you’re falling asleep randomly, we asked Dr. Chester Wu for his thoughts. Dr Wu is one of our Rise Science sleep advisors and medical reviewers, and he’s double board certified in psychiatry and sleep medicine.

“If you’re falling asleep randomly, the most likely cause is sleep deprivation. Try getting a little more sleep at night to see if that helps you stay awake. Falling asleep often can also be a sign of a medical condition or sleep disorder, like narcolepsy. Speak to your healthcare provider to rule out any underlying causes.”

High Sleep Debt

In many cases, sleep debt is the primary reason why you're falling asleep randomly.

Sleep debt is the amount of sleep you’ve missed out on recently. If you haven’t been meeting your sleep need — the genetically determined amount of sleep you need — you’ll have built up sleep debt. And the more sleep debt you have, the more likely you are to fall asleep during the day. 

One sleep study looked at healthy participants who restricted their sleep to four hours a night for seven nights. The results showed the number and duration of microsleeps (falling asleep for short periods of time) they experienced increased. They even experienced microsleeps when they first started to get more sleep. 

Learn how long it takes to recover from sleep deprivation here.

Microsleeps can be short — up to 15 seconds — and you may not even notice them. Your performance is impaired when it happens, which can be incredibly dangerous if you fall asleep while driving

Sometimes it’s obvious when you haven’t been getting enough sleep lately. But you may also need more sleep than you think. 

For example, when we looked at the sleep needs of 1.95 million RISE users, we found 48% of them need eight hours of sleep or more. Sleep needs ranged from five hours to a whopping 11 hours 30 minutes!

The RISE app can tell you how much sleep you need.
The RISE app can tell you how much sleep you need.

 

The fix: Lower your sleep debt. RISE works out how much sleep you need and whether you’ve got any sleep debt. If you’ve got a lot, you can lower your sleep debt by heading to bed a little earlier, sleeping in a little later, taking short daytime naps, or improving your sleep hygiene (more on that soon). 

RISE app screenshot showing how much sleep debt you have
The RISE app calculates how much sleep debt you’ve got.

Expert tip: You may temporarily need more sleep than usual when you’re recovering from illness, intense exercise, or injury (a 2023 study found muscle injury caused participants to sleep for longer). Try taking a short afternoon nap to see if that helps you stay awake. 

We’ve covered more advice on how to feel more awake here.

RISE users on iOS 1.202 and above can view their sleep debt here

Not Being in Sync With Your Circadian Rhythm 

Your circadian rhythm is your roughly 24-hour body clock that helps to control your sleep cycle. 

You can get out of sync with your circadian rhythm by: 

  • Working night shifts
  • Having an irregular sleep schedule (which about 87% of us do) 
  • Fighting your chronotype — like night owls trying to wake up early 
  • Traveling across time zones — you might be falling asleep at bedtime back home if you’re jet-lagged 

When you’re out of sync with your circadian rhythm, you can feel low on energy and find yourself nodding off at seemingly random times. 

The fix: Get in sync with your circadian rhythm. You can do this by keeping a regular sleep pattern, eating your meals at regular times, and checking RISE to see when your body wants to go to sleep (look out for your Melatonin Window) and wake up. 

RISE predicts the timing of your circadian rhythm each day, so you can sync up your daily life with it. 

RISE app screenshot showing your energy schedule
The RISE app predicts the timing of your circadian rhythm each day.

Heads-up: Sleep debt and being out of sync with your circadian rhythm are the two most common reasons for falling asleep during the day. Many other causes feed into these two things. For example, sleep disorders, anxiety, and alcohol consumption can cause you to rack up sleep debt, which can lead to daytime tiredness and nodding off randomly. 

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Narcolepsy 

Narcolepsy is a neurological condition that causes you to feel sleepy and fall asleep randomly during the day. You may not be able to control your sleep-wake cycles, either. 

The symptoms of narcolepsy include: 

  • Falling asleep randomly (also known as sleep attacks): Sleep attacks can happen at any time and sometimes without warning. You could be eating, working, or talking and suddenly fall asleep. This spontaneous sleep can last a few seconds, minutes, or even up to half an hour, and it can happen several times a day. Your body may carry on doing the activity you were doing before you fell asleep, like typing or writing.
  • Excessive daytime sleepiness (EDS): People with narcolepsy experience excessive sleepiness. You might feel sleepy all the time, struggle to focus, and have memory problems. This can happen even if you get enough sleep at night. 
  • Cataplexy: Or sudden loss of muscle tone and muscle control. This can cause slurred speech, muscle weakness, or collapse. Cataplexy can be triggered by strong emotions like anger or laughter. There are two types of narcolepsy: type 1 narcolepsy, which often involves cataplexy, and type 2 narcolepsy, which often doesn’t involve cataplexy (type 2 is more common). 
  • Sleep paralysis: Sleep paralysis is when you can’t move or speak as you transition from being asleep to being awake. 
  • Hallucinations: You may have hallucinations as you’re falling asleep, known as hypnagogic hallucinations, or when you’re waking up, known as hypnopompic hallucinations. You might also get vivid or excessive dreams that cause sleep disruptions.  
  • Sleep problems: Despite feeling tired and falling asleep in the day, you may have sleep problems come nighttime, like insomnia or sleep apnea. 
  • Changes in REM sleep: People with narcolepsy may enter the rapid-eye-movement (REM) stage of sleep much sooner than those without the condition. This can happen during their daytime sleep, too, and they may also act out their dreams while in REM. 

It’s not clear what the causes of narcolepsy are. For some, the condition can be caused by low levels of hypocretin (a.k.a. orexin), a brain chemical that helps you stay awake. 

You’re more at risk of narcolepsy if you have a family history of the sleep disorder. And it may be caused by hormonal changes during puberty or menopause, major stress, or infections like swine flu. Narcolepsy is more common in women (as are many sleep disorders). 

It can be diagnosed with a polysomnogram, a sleep study, or a multiple sleep latency test (MSLT). A MSLT measures how quickly you fall asleep and enter REM. 

The fix: If you’re experiencing narcolepsy symptoms, speak to your healthcare provider or a sleep specialist. There’s no cure for narcolepsy, but treatment options can involve taking short naps throughout the day, keeping a strict sleep schedule, improving your sleep hygiene (keep reading for what that looks like), and medication like modafinil, sodium oxybate, amphetamine-like stimulants such as methylphenidate, and serotonin-norepinephrine reuptake inhibitors (SNRIs). 

Insomnia 

Insomnia is the most common sleep disorder out there. 

There are four key types of insomnia: 

  • Sleep onset insomnia: Trouble falling asleep. 
  • Sleep maintenance insomnia: Trouble staying asleep. 
  • Early morning awakening insomnia: Waking up too early
  • Mixed insomnia: A combination of the above. 

You might associate insomnia with not falling asleep, but those with insomnia likely have a lot of sleep debt from being awake during the night, and this can cause them to fall asleep during the day. Insomnia can be a long-term problem, too, causing some serious sleep debt to build up. 

The fix: Talk to your healthcare provider if you regularly struggle to sleep. Insomnia can be treated with cognitive behavioral therapy for insomnia (CBT-I), which includes techniques like relaxation training and, counterintuitively, sleep restriction.   

Sleep Apnea

Obstructive sleep apnea causes you to stop breathing throughout the night. Your airways relax and temporarily close, cutting off your breathing for 10 seconds or more. This can happen 30 times or more an hour. 

When your brain figures out what’s going on, it’ll wake you up to kickstart your breathing again. This sleep disruption can lead to — you guessed it — sleep debt. 

You can learn more about how to know if you’ve got sleep apnea here.

The fix: Get medical advice. Sleep apnea treatments will vary depending on how serious your condition is. For some, sleeping on their side or losing weight can help. Others may need to sleep with a continuous positive airway pressure (CPAP) machine. 

Anxiety or Depression 

Mental health issues like anxiety and depression can cause you to feel run down and fatigued during the day. But they can also keep you up at night, adding to potential sleep debt. 

RISE users say anxiety and depression are the two biggest barriers to getting a good night’s sleep. 

The fix: Talk to a healthcare professional if you think you’re suffering from a mental health issue. If general day-to-day stress and anxious thoughts are disrupting your sleep, try implementing a relaxing bedtime routine. Spend the hour before bed reading, taking a warm shower or bath, and doing breathing exercises

We’ve covered how to sleep with anxiety here.

RISE can guide you through breathing exercises and relaxation techniques to help you drift off. 

RISE app screenshot showing relaxation session reminders
RISE can help you fall asleep faster with breathing and relaxation exercises.

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Hypersomnia

Hypersomnia causes you to sleep for long periods of time and still feel sleepy when you’re awake. It’s a rare sleep disorder affecting 4% to 6% of the population. 

Some people with hypersomnia fall asleep repeatedly throughout the day, but this sleep doesn’t give them any relief from their symptoms. 

Hypersomnia can be caused by: 

  • Medical conditions like Parkinson’s disease and multiple sclerosis 
  • Sleep disorders like sleep apnea and restless leg syndrome 
  • Drug or alcohol abuse 

Idiopathic hypersomnia is when there’s no known cause for the disorder. 

You can learn more about hypersomnia here.

The fix: Talk to your healthcare provider if you think you’ve got hypersomnia. They may recommend medication or lifestyle changes to reduce your symptoms. 

Restless Leg Syndrome 

Restless leg syndrome (RLS) is another sleep disorder that can eat into your sleep time and cause you to rack up sleep debt. 

Symptoms include:

  • Unpleasant sensations in the legs
  • A strong urge to move your legs
  • Involuntary movements in your legs

These symptoms can sometimes happen in other areas of your body, and they’re worse when sitting or lying down and at night. 

A 2023 meta-analysis found RLS is more common among women and older adults. 

The fix: Seek medical advice. Treatment options involve lifestyle changes (like avoiding caffeine and alcohol), massage, exercise, and supplements and medications if needed. 

Alcohol 

Alcohol can make you fall asleep randomly for two reasons: 

  1. It acts as a sedative: If you’re enjoying a glass of wine in front of the TV (and perhaps you’re already sleep deprived), you may be hit with a wave of drowsiness and nod off. 
  2. It disrupts your sleep: Research from 2019 shows alcohol can trigger insomnia, shorten your sleep duration, increase how much you snore, and cause you to wake up in the night. This can lead to sleep debt and falling asleep the next day. 

The fix: Avoid alcohol three to four hours before bed to stop it from causing sleep disruptions. RISE can tell you when exactly to have your final drink each day. 

You can learn more about when to stop drinking alcohol before bed here.

RISE app screenshot showing when to avoid alcohol
The RISE app can tell you when to stop drinking alcohol before bed.

RISE users on iOS 1.202 and above can set up their avoid late alcohol reminder here.

Medical Conditions 

Medical conditions could be disrupting your sleep, causing you to feel tired and fall asleep randomly. 

These include: 

  • Hypothyroidism (underactive thyroid) 
  • Kidney disease 
  • ADHD 
  • COVID
  • Anemia 
  • Obesity 
  • Heart disease 
  • Type 2 diabetes 
  • High blood pressure 

While not medical conditions, your period, pregnancy, and menopause can cause sleep problems, making it more likely you’ll fall asleep randomly. 

The fix: Talk to your doctor. They can test you for any underlying health conditions that could be making you fall asleep and recommend the best treatment options to help. 

Medications 

Medications can cause side effects like daytime fatigue or sleep issues. 

These include: 

  • Antidepressants
  • Antihistamines 
  • ADHD drugs 
  • Antipsychotics 
  • Blood pressure meds 
  • Birth control 

Plus, if you take melatonin at the wrong time, you could find yourself feeling sleepy and falling asleep during the day when that wasn’t your plan. 

The fix: Talk to your doctor about your meds. They may be able to recommend changes to your prescription or lifestyle changes to help. If you’re on hormonal birth control, try switching up your method to one that doesn’t use hormones or one that uses lower doses of hormones. And if you take melatonin, you can learn how long before bed to take melatonin here to avoid feeling sleepy at the wrong time.

Poor Sleep Hygiene 

Sleep hygiene is the name for the daily habits that influence how well you sleep. If you’ve got poor sleep hygiene, you may find it harder to fall asleep, wake up more often in the night, and your sleep might be more restless. All this can up your odds of drifting off the next day. 

Poor sleep hygiene includes: 

  • Sleeping in a bedroom that’s too warm, too bright, or too noisy  
  • Not getting out in daylight in the morning or during the day 
  • Getting too much bright light in the run-up to bedtime 
  • Drinking caffeine or alcohol, doing intense exercise, or eating a large meal close to bedtime 

The fix: Improve your sleep hygiene. RISE can guide you through 20+ sleep hygiene habits each day. Follow these habits to get more sleep and make sure the sleep you get is as restorative as possible. 

RISE app screenshot reminding of sleep hygiene habits
The RISE app can tell you when to do 20+ sleep habits.

RISE users on iOS 1.202 and above can set up their 20+ in-app habit notifications here

We’ve covered more on why you’re always sleepy no matter how much sleep you get here.

Stop Falling Asleep Randomly and Get More Energy 

It can be worrying — and downright dangerous — if you find yourself falling asleep randomly. While this can be caused by sleep disorders and medical conditions, the two most likely culprits are high sleep debt and being out of sync with your circadian rhythm. 

To fix these, turn to the RISE app. RISE can work out how much sleep you need and how much sleep debt you have. The app will keep track as you work to pay back your sleep debt. 

RISE can also predict your circadian rhythm each day, to help you stay in sync, and guide you through 20+ sleep hygiene habits, to help you get the sleep you need at night to stay awake during the day. 

We found 80% of RISE users feel more energy within five days — so you could stop snoozing randomly within the week.

Summary FAQs

What causes you to fall asleep randomly?

The two most common causes of falling asleep randomly are high sleep debt or being out of sync with your circadian rhythm. Falling asleep randomly can also be caused by narcolepsy, sleep apnea, alcohol, anxiety, depression, or medical conditions like diabetes and anemia.

Why do I keep falling asleep during the day?

You probably keep falling asleep during the day because you’ve got a lot of sleep debt or you’re out of sync with your circadian rhythm. You may also be falling asleep during the day due to narcolepsy, sleep apnea, alcohol, anxiety, depression, or medical conditions like diabetes and anemia.

Why do I keep falling asleep when I sit down?

You probably keep falling asleep when you sit down because you’ve got a lot of sleep debt or you’re out of sync with your circadian rhythm. You may also be falling asleep when you sit down due to narcolepsy, sleep apnea, alcohol, anxiety, depression, or medical conditions like diabetes and anemia.

Why do I randomly fall asleep for a few seconds?

You’re probably falling asleep for a few seconds (also known as a microsleep) because you’ve got a lot of sleep debt or you’re out of sync with your circadian rhythm. Other causes include narcolepsy, sleep apnea, anxiety, depression, alcohol, or medical conditions like diabetes and anemia.

Why do I fall asleep when reading or watching TV?

You probably keep falling asleep when reading or watching TV because you’ve got a lot of sleep debt or you’re out of sync with your circadian rhythm. You’re less stimulated and active when reading or watching TV, so it’s easier to drift off. You may also be falling asleep randomly due to narcolepsy, sleep apnea, alcohol, anxiety, depression, or medical conditions like diabetes and anemia.

What sleep disorder mimics narcolepsy?

Hypersomnia is a sleep disorder that mimics narcolepsy in some ways. People with hypersomnia sleep a lot and feel tired during the day. Sleep disorders like insomnia, sleep apnea, and restless leg syndrome can cause a lot of sleep debt, which can cause narcolepsy-like symptoms such as falling asleep randomly.

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