Can't Wake Up? Why You Sleep Through Alarms

On Reddit’s sleep community this week, one post drew hundreds of comments. The writer described setting eight alarms, five minutes apart, sleeping through every one, and losing a well-paid job as a result. The replies were full of people with the same problem: phones vibrating across the room, partners shaking them awake, and the creeping fear of a missed flight or shift.

If that sounds familiar, you’re not lazy and you’re not alone. Sleeping through alarms usually has a cause, and most causes have practical fixes. Here’s why it happens, what actually helps, and when it’s worth seeing a sleep specialist.

Why some people sleep through alarms

1. You’re not getting enough sleep

This is the big one. If you’re short on sleep, your brain is under strong pressure to stay asleep, and an alarm that would normally wake you may not be enough. About 27% to 28% of US adults sleep less than seven hours on average, according to CDC data from the 2020 National Health Interview Survey (CDC, 2022), so it’s a very common problem.

Sleep debt also makes waking up feel worse. Sleep inertia, the groggy, heavy feeling after waking, is stronger after sleep loss. In one study of chronic sleep restriction that’s summarized in a review by Cassie Hilditch and Andrew McHill, performance didn’t return to baseline until about 70 minutes after waking (Hilditch and McHill, 2019, Nature and Science of Sleep).

2. Your alarm goes off during your biological night

Your body clock sets when you naturally feel sleepy and alert. If it runs late, as it does for many night owls, a 6 a.m. alarm may go off at what your body treats as the middle of the night.

The Hilditch and McHill review notes that sleep inertia is strongest when you wake during the biological night. It also found that full recovery from sleep inertia often takes at least an hour, and later chronotypes may take longer.

This is why the same alarm can feel impossible in winter, when dark mornings and less daylight tend to push body clocks later. Our guide to waking up on dark winter mornings covers that seasonal side.

3. Your schedule is irregular

Sleeping in until 10 a.m. on weekends and getting up at 6 a.m. on weekdays is like flying a few time zones west every Friday and back every Monday. Monday’s alarm then lands at an even worse point in your body clock.

4. Your alarm is easy to dismiss half-asleep

Many people don’t sleep through the alarm so much as turn it off without fully waking, and then don’t remember doing it. A phone next to the pillow makes that very easy.

5. Alcohol, sedating medications or sleep aids

Alcohol close to bedtime disrupts sleep and can leave you groggy. Some medications, including certain sleep aids, sedating antihistamines and some antidepressants, can also make you harder to rouse or groggier the next morning. The FDA warned in 2013 that people taking insomnia medications can be impaired the morning after, even if they feel fully awake. Don’t change or stop any prescribed medication on your own, but if you suspect it’s affecting your mornings, ask your doctor or pharmacist.

6. ADHD and late body clocks

On r/ADHD, threads about how hard mornings are regularly draw hundreds or thousands of replies. There’s research behind that experience. A Dutch study of 40 adults with ADHD found that those with trouble falling asleep, who made up most of the group, had later sleep timing and a later rise in the sleep hormone melatonin than adults without ADHD (van Veen et al., 2010, Biological Psychiatry). It was a small study, and not everyone with ADHD has a delayed clock, but it suggests that for some people the problem is timing, not willpower.

If you have ADHD, the strategies below still apply, and external cues like light, a set routine and alarms you can’t silence from bed tend to work better than relying on motivation. Talk to the clinician who manages your ADHD about sleep. It’s a common and legitimate topic.

7. A sleep disorder

Sometimes there’s a medical cause. Possibilities a doctor might consider include:

• Delayed sleep-wake phase disorder (DSWPD). One of the most common circadian rhythm disorders. You fall asleep much later than you want and have real trouble getting up on time, which leads to short sleep and daytime tiredness (NHLBI).
• Sleep apnea. Repeated breathing interruptions fragment your sleep, so you wake up unrefreshed and sleepy no matter how long you were in bed. Loud snoring and gasping are common signs. (If you’ve been tempted to tape your mouth to stop snoring, read what the research says about mouth taping first.)
• Idiopathic hypersomnia. A neurologic sleep disorder marked by excessive daytime sleepiness and “sleep drunkenness,” a severe form of sleep inertia that can make waking extremely difficult (Hypersomnia Foundation).
• Other causes such as depression, thyroid problems or narcolepsy can also cause excessive sleepiness.

You can’t diagnose these yourself, and that’s not the goal here. The point is that if the practical fixes don’t help, there may be something treatable going on.

Practical fixes that actually help

No single trick works for everyone. The most reliable approach is to stack several wake-up signals so you’re not relying on one sound.

Get more sleep first

Unglamorous but essential. Work backward from your wake time and aim for at least seven hours in bed asleep. If you need to be up at 6:30, that usually means lights out by about 11 at the latest. If you’re getting much less, no alarm will fully solve the problem.

Keep the same wake time, seven days a week

A consistent wake time is one of the best tools for anchoring your body clock. Keep weekends within about an hour of weekdays. If you’re trying to get up earlier than your body wants, shift in 15-minute steps every few days, as we explain in how to become a morning person.

Move the alarm across the room

Put your main alarm where you have to stand up and walk to turn it off. That’s often enough to break the half-asleep dismiss cycle. Charging your phone outside the bedroom and using a separate alarm clock also removes the temptation to scroll in bed.

Add light before the alarm

A sunrise alarm gradually brightens your room before your wake time. The evidence is small, but in a home study of people who struggled with early waking, a simulated dawn reduced grogginess on waking (Giménez et al., 2010, Chronobiology International). For heavy sleepers, choose one with a long sunrise and a real sound alarm. The Lumie Bodyclock Shine 300 (opens in a new tab) lets you set the sunrise anywhere from 15 to 90 minutes. See our researched picks of the best sunrise alarm clocks for more options, and keep a loud backup alarm regardless.

Use more than one sense

If sound alone isn’t working, add touch:

• A vibrating alarm, such as a smartwatch or fitness band with a silent alarm, or a bed shaker that goes under your pillow or mattress. Bed shakers are widely used by people who are deaf or hard of hearing, and many heavy sleepers find them hard to ignore.
• A different sound. In a small survey of 50 people, those who woke to alarms they rated as melodic reported less grogginess than those with neutral-sounding alarms (McFarlane et al., 2020, PLOS One). It’s an early, self-reported finding, but switching from a harsh beep to a song you like costs nothing to try.

Rethink the snooze button

Snoozing has a bad reputation, but the evidence is more nuanced. In a Stockholm University study, 31 regular snoozers who were allowed to snooze for 30 minutes didn’t lose much sleep, weren’t worse off for mood or sleepiness, and actually did slightly better on thinking tests right after getting up than when they had to get up immediately (Sundelin et al., 2023, Journal of Sleep Research). The researchers stressed that this only applied to habitual snoozers who fall back asleep easily.

So if one planned snooze works for you, it’s probably fine. Eight alarms five minutes apart is a different situation. It usually signals that you’re short on sleep or waking at the wrong point in your body clock, and the extra alarms can teach you to tune them out.

Do 90-minute sleep cycle calculators work?

You’ve probably seen the viral charts: pick your wake time, count back in 90-minute blocks, and go to bed at exactly 9:46 or 11:16 to wake up “between cycles.” The idea is half right.

The right half: waking from deep (slow-wave) sleep tends to make sleep inertia worse than waking from lighter sleep (Tassi and Muzet, 2000, Sleep Medicine Reviews). So where you are in your sleep when the alarm goes off does matter.

The wrong half: the chart assumes every cycle is exactly 90 minutes and that you fall asleep the moment you lie down. Neither is true. The US National Heart, Lung, and Blood Institute describes cycles that restart roughly every 80 to 100 minutes, with four to six cycles a night (NHLBI). Ten minutes of difference per cycle adds up to most of an hour by morning, before you count the time it takes to fall asleep. A clock-based chart can’t know where you really are.

What the chart gets accidentally right is the structure of the night: deep sleep is concentrated early, and later cycles carry more REM and lighter sleep (also NHLBI). If you get enough sleep and wake at a consistent time, your alarm is more likely to land in lighter sleep anyway. That makes the dull advice more reliable than the math: enough sleep, the same wake time every day, and light soon after you get up.

Make getting up easier than staying in bed

• Have bright light ready: switch on overhead lights or a lamp as soon as your feet hit the floor.
• Get outside within an hour of waking if it’s light out. Daylight is the strongest signal for your body clock, as we explain in our guide to morning sunlight.
• Give yourself a reason to get up: coffee set to brew, a pleasant 10-minute ritual or a short walk.

Use an accountability backup for high-stakes mornings

For a flight, an exam or a new job, don’t rely on yourself alone. Ask a partner, roommate or friend to call you or check that you’re up. Some people pay for a wake-up call service. It isn’t a long-term solution, but it buys time while you fix the underlying problem.

When to see a sleep specialist

Start with your primary care doctor, who may refer you to a sleep specialist. It helps to bring a two-week sleep diary showing when you went to bed, roughly when you fell asleep, when your alarms went off, when you actually got up and how you felt. Note any medications, alcohol and caffeine too. Depending on your symptoms, a specialist may suggest a sleep study or a period of wearing an activity tracker to look at your sleep timing.

What to do tomorrow morning

1. Tonight, count back seven and a half hours from your wake time and aim to be in bed by then.
2. Move your alarm across the room, and charge your phone outside the bedroom if you can.
3. Add a second, different signal: a vibrating alarm on your wrist, a bed shaker or a sunrise light.
4. Switch on bright lights the moment you’re up, and get outside soon after sunrise if you can.
5. Start a simple sleep diary. If you’re still sleeping through alarms after two weeks of enough sleep and a steady schedule, take it to a doctor.