What Three Snooze Alarm Studies Found (Mattingly, Ogawa, Robbins)

Does snoozing leave you groggier than getting up on the first alarm? In the one laboratory trial that tested it, yes, slightly, but that trial had 10 participants. The two larger studies describe who snoozes and how much, and they do not measure what it costs. Here are the three papers a reader keeps hearing about second-hand, taken in the order a skeptic would ask for them.

Is there a lab experiment on snoozing?

The only one a Europe PMC search for snooze alarm studies turned up is Ogawa, Kaizuma-Ueyama and Hayashi (2022, Journal of Physiological Anthropology). Ten Japanese university students who already snoozed five to seven times a week slept in a lab for two recorded nights, one with a phone snooze alarm and one without, in counterbalanced order. The snooze condition rang four times at 5-minute intervals across the final 20 minutes before the target wake time.

Polysomnography showed the difference clustered in those 20 minutes. With the snooze alarm, participants slept 15.7 minutes of the 20 on average, against 19.7 without it (p = 0.002), were aroused 4.1 times against 0.3, and spent more time awake and in light N1 sleep. Reaction time on a simple beep task was slower in the last of three post-waking sessions with snoozing, 238.4 ms against 221.9 ms (p = 0.024). The overall condition effect on reaction time was not significant, and the authors report a post hoc power of 0.47, so this is a signal from a small sample, not a settled result. They also found that Global Vigor, a self-rated scale, rose after waking in the no-snooze condition compared with before sleep, which the snooze condition did not show.

Hayashi’s group concludes that snoozing prolongs sleep inertia, the groggy, impaired state right after waking, “possibly because snooze alarms induce repeated forced awakenings.” For how long that state can last after any waking, see Burke’s 2015 study of attention after waking.

Who snoozes, and is their sleep different?

Mattingly, Martinez, Young, Cain and Striegel (2022, Sleep) surveyed 450 participants and combined the answers with wearable data. They counted snoozing as using multiple alarms to wake, and 57% of the sample did. Being female, younger, less conscientious, a more evening type, having more disturbed sleep and taking fewer steps each raised the odds of being a snoozer. Snoozers showed lighter sleep before waking and a higher resting heart rate. They did not sleep fewer hours than non-snoozers, and they did not report more sleepiness or more napping.

Two cautions come from the authors themselves. Consumer wearables stage sleep imperfectly, especially around transitions, and the authors say so. Their study also never measured grogginess after waking. Heart rate during interrupted sleep has its own, separate trials, covered in a post on snoozing and cardiovascular measures.

How common is snoozing in a huge sample?

Robbins, Sääf, Weaver, Gradisar, Quan and Czeisler (2025, Scientific Reports) analysed more than 3 million nights from 21,222 users of the SleepCycle app over about six months. On logged nights, 55.6% ended with a snooze. Among those mornings the average was 2.4 presses and 10.8 minutes. Weekdays had more snoozing than weekends, women pressed slightly more often than men (2.5 against 2.3), and the month with the most snoozing was December in the Northern Hemisphere. Longer sleep sessions, over nine hours, ended in a snooze more often than 7 to 9 hour ones, and going to bed later than usual was linked with more snoozing the next morning.

Eleven minutes a morning adds up to roughly 5.5 hours over a 30-day month (my arithmetic: 11 x 30 = 330 minutes), a figure the authors frame as nearly one night of sleep. Their limits are stated plainly. The data come from people who chose a sleep-tracking app, there was no age information and no record of how people felt afterwards, and users may have been awake and scrolling between presses, so the paper says it likely overestimates snooze use.

What do the three add up to?

Together they establish three things and leave three open. Established: snoozing is common (somewhere between 55% and 70% of mornings or people, depending on the sample and definition), it clusters in the heavy tail rather than evenly, and in a small lab trial it fragments the last 20 minutes of sleep. Open: whether the grogginess cost is large in real life, whether snoozing shortens anyone’s total sleep, and whether the lighter pre-waking sleep in Mattingly’s snoozers is a cause or just a trait of evening types.

The practical reading is narrower than the headlines. If you snooze once or twice for 3 to 6 minutes, nothing here says you are harming yourself. If you are in the heavy group, four presses and 20 minutes most mornings, the evidence says you are sleeping in short broken pieces, which is a poor trade even if its price is unmeasured. Moving the real wake time to when you actually get up is the cleaner option, and a fixed wake time is the anchor in CBT-I for a similar reason.

If you want the first alarm to be the only one, DontSnooze is a free iOS and Android app that gives you 30 seconds after the alarm to record a short video showing you are up.

Ogawa’s finding about anxiety deserves a last word. Seventy point five percent of the 289 students who used any wake-up tool often used a phone snooze, and half gave worry about not waking on time with a single alarm as the reason. The paper does not say the habit is irrational. It says the fear is real, the cost is a few minutes of fragmented sleep, and the only way to find out which side wins for you is to try one week with a single reliable alarm and see how you feel at nine.