The most common signs of sleep deprivation are trouble focusing, a short temper, daytime sleepiness and slower reactions. The NHLBI says people who are short on sleep may have trouble learning, focusing and reacting, and may feel frustrated, cranky or worried in social situations (NHLBI). This guide lists the signs, explains the safety risks and tells you when to see a doctor. It is for education and cannot diagnose you.
Think you may owe your body sleep? Check the size of your debt with the sleep debt calculator.
What Is Sleep Deprivation?
Sleep deprivation means not getting enough sleep. The NHLBI uses a wider term, sleep deficiency. It includes not sleeping enough, sleeping at the wrong time of day, not sleeping well, and having a sleep disorder that blocks enough or good sleep (NHLBI). So you can feel deprived even if you spend eight hours in bed.
How much is enough? The CDC says adults aged 18 to 60 need at least seven hours a night. School-age children need 9 to 12 hours, and teens need 8 to 10 (CDC).
Common Signs Of Sleep Deprivation
No single sign proves it, but several together are a strong hint.
- Trouble thinking. The NHLBI lists trouble learning, focusing and reacting (NHLBI).
- Mood changes. You may feel irritable or lack motivation, and feel too tired to work well, exercise or eat well (Harvard Health).
- Daytime sleepiness. Harvard Health also lists daytime drowsiness and brief sleep lapses called microsleeps (Harvard Health).
- Feeling tired after enough sleep. The CDC names this as a sign of poor sleep quality, along with trouble falling asleep and waking repeatedly in the night (CDC).
- Reading people less well. The NHLBI notes that you may struggle to judge other people’s emotions and reactions (NHLBI).
- Catching more colds. Harvard Health says you may be more likely to catch a cold after exposure to a virus (Harvard Health).
Mood links run both ways. Read how sleep affects your emotions and sleep and depression.
How Sleep Loss Affects Your Thinking
Being awake too long can slow you down as much as alcohol does in some tasks. In a study of 39 people, performance after 17 to 19 hours awake was equal to or worse than performance at a blood alcohol level of 0.05 percent on some tests. After longer without sleep, it reached levels like the highest alcohol dose tested, 0.1 percent (Williamson and Feyer 2000). This was true for some tests, not all of them.
Small nightly shortfalls add up too. In a study of 48 healthy adults aged 21 to 38, limiting sleep to six hours or less per night led to thinking deficits equal to up to two nights of no sleep at all (Van Dongen et al. 2003). That is why a “mild” habit of short sleep deserves attention. See how to recover from sleep debt.
Microsleeps And Driving
A microsleep is a brief bout of sleep during the day, usually lasting just a few seconds. It can last 10 to 15 seconds, and during one you may not respond to sounds or events around you (Harvard Health). That is dangerous behind the wheel.
The NHLBI says sleepiness while driving, not linked to alcohol, causes serious crash injuries and deaths (NHLBI). In a CDC survey of 92,102 adults, 4.0 percent said they had fallen asleep while driving in the past 30 days. Among those who usually slept five hours or less, it was 9.1 percent (CDC MMWR). Harvard Health reports estimates of about 1,550 deaths and 40,000 non-fatal injuries a year in the United States (Harvard Health).
If you nod off, miss an exit or cannot remember the last few miles, pull over and rest or switch drivers. Do not push on.
Long-Term Signs And Health Risks
Ongoing sleep loss does more than make you groggy. The NHLBI links sleep deficiency to heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity and depression. It can also lead to injuries and lost productivity, and raises the chance of falls and broken bones in older adults (NHLBI). Harvard Health adds anxiety to the list and says ongoing sleep loss raises the risk of chronic problems including obesity and diabetes (Harvard Health).
These are links found in research, not a guarantee that short sleep will cause any one illness in you. For more on this, see poor sleep and inflammation and the chronic sleep deprivation risk calculator.
Signs In Children And Teens
Kids do not always look sleepy. The NHLBI says sleep-deficient children may be overly active, have trouble paying attention, misbehave, and do worse at school (NHLBI). Recommended sleep is 9 to 12 hours for ages 6 to 12 and 8 to 10 hours for ages 13 to 17 (CDC). Read more in teen sleep deprivation.
A Quick Self-Check
Ask yourself these questions over the past two weeks. None of them is a diagnosis, but a pattern of “yes” answers is worth acting on.
- Do I need an alarm and several snoozes to get up, and still feel foggy?
- Do I reread things or lose my train of thought more than usual?
- Have I snapped at people over small things?
- Do I feel drowsy in meetings, in class or while reading?
- Do I rely on caffeine to get through the afternoon?
- Have I nodded off, even for a second, when I did not mean to?
Keep a simple sleep diary for a week. Write down when you went to bed, when you woke and how you felt. It makes the pattern easier to see, and a provider may ask for one. The CDC notes that a provider may request a sleep diary or order sleep studies (CDC). Be careful with sleep trackers, since they are rough guides. See are sleep trackers accurate.
One more point: tired people are poor judges of their own tiredness. If friends or family say you seem short-tempered or spaced out, take that seriously.
Could It Be A Sleep Disorder?
If you sleep long enough but still feel exhausted, a sleep disorder may be the cause. The NHLBI counts a disorder that prevents enough or good sleep as part of sleep deficiency (NHLBI). Two to know:
- Insomnia. The NHS lists trouble falling asleep, waking several times, lying awake, waking early and feeling tired and irritable in the day (NHS). See how to beat insomnia.
- Sleep apnea. The NHS lists breathing that stops and starts, gasping, snorting or choking noises, loud snoring, and daytime tiredness and poor concentration. It warns the condition can be serious if not diagnosed and treated (NHS). See sleep apnea health risks.
Our guide to signs you have a sleep disorder goes into more detail.
When To See A Doctor
The CDC advises talking to your healthcare provider if you have problems sleeping. A provider can run tests, including sleep studies, to find out whether you have a sleep disorder (CDC). The NHS suggests seeing a GP if changing your sleep habits has not helped, you have had trouble sleeping for months, or it affects your daily life in a way that makes it hard to cope (NHS). It also advises a visit if your breathing stops and starts while you sleep, or you always feel very tired during the day (NHS).
What Helps
If the cause is simply too little sleep, the fix is more sleep, added gradually. Start with how to recover from sleep debt, set a bedtime with the bedtime calculator, and build habits from sleep hygiene 101.
FAQs About Sleep Deprivation
What Are The First Signs Of Sleep Deprivation?
Early signs include trouble focusing, slower reactions, irritability and daytime drowsiness (NHLBI, Harvard Health).
Can You Be Sleep Deprived And Not Feel Tired?
How Does Sleep Deprivation Affect Driving?
It raises the risk of microsleeps and crashes. In a CDC survey, 9.1 percent of people who usually slept five hours or less had fallen asleep at the wheel in the past month (CDC MMWR).
How Many Hours Of Sleep Do You Need?
At least seven hours for adults aged 18 to 60. Teens need 8 to 10 hours and school-age children 9 to 12 (CDC).
What Are The Long-Term Effects Of Sleep Deprivation?
The NHLBI links sleep deficiency to heart disease, high blood pressure, diabetes, stroke, obesity and depression (NHLBI).