How much sleep do you need?
The American Academy of Sleep Medicine recommends 7 or more hours of sleep each night for adults. For teenagers from 13 to 18 years, it recommends 8 to 10 hours.
| You get up at | Asleep by, for 7 hours | Asleep by, for 8 hours | Asleep by, for 9 hours |
|---|---|---|---|
| 6:00 am | 11:00 pm | 10:00 pm | 9:00 pm |
| 6:30 am | 11:30 pm | 10:30 pm | 9:30 pm |
| 7:00 am | 12:00 am | 11:00 pm | 10:00 pm |
| 7:30 am | 12:30 am | 11:30 pm | 10:30 pm |
These are the times when you are asleep, not the times when you go to bed. Add the time that you need to fall asleep.
Why is the first half hour so hard?
The grogginess after waking is named sleep inertia. A 2019 review reports that performance often returns to normal in 15 to 30 minutes, and that full recovery can take an hour or more. Too little sleep makes sleep inertia worse.
Plan for it. Get up 30 minutes or more before you must think clearly. See what sleep inertia is and how long it lasts.
What can you do the evening before?
- Set one alarm for the latest time that still gets you to class.
- Put the phone where you must stand up to reach it.
- Pack your bag and put out your clothes.
- Decide your first action after the alarm, for example a shower or breakfast.
- Go to bed at the time from the table.
What can you do when the alarm rings?
- Stand up before you stop the alarm.
- Turn on the light or open the curtains.
- Do not go back to bed "for five minutes". See how to wake up without falling back asleep.
- Start your first action at once.
Does snoozing help students?
Snoozing is common among students. In a 2022 survey of 293 university students in Japan, 70.5% said that they often use the snooze function. The research does not show that snoozing is harmful, but each snooze moves your morning nearer to the start of class. See how to stop snoozing your alarm.
Can a talking alarm help?
Waker is an iPhone alarm app that has no snooze button. When your alarm rings, you tap “Talk to Waker” and have a voice conversation about your day. You can tell Waker your goals for the day, so the call can start with your class. Waker needs a subscription and an iPhone with iOS 26 or later. No study has tested if a conversation gets students to class more often.
Common questions
Why do I sleep through my alarm before class?
The usual reason is too little sleep. A late bedtime on free days can also move your body clock later, and then the alarm rings in your biological night. See why you cannot wake up to your alarm.
Is it better to set many alarms?
Many alarms break the last part of your sleep. One alarm at the latest possible time gives you more unbroken sleep. See if it is bad to set many alarms.
Should I sleep late on weekends?
A much later wake-up time on free days makes Monday harder, because your body clock moves later. Keep the difference small.
What if I still cannot wake up?
Speak to a doctor if you sleep enough hours and still cannot wake up, or if you are very sleepy in the daytime for weeks.
Sources
- Recommended amount of sleep for a healthy adult: a joint consensus statement. American Academy of Sleep Medicine and Sleep Research Society, Journal of Clinical Sleep Medicine, 2015.
- Recommended amount of sleep for pediatric populations: a consensus statement. American Academy of Sleep Medicine, Journal of Clinical Sleep Medicine, 2016.
- Sleep inertia: current insights. Hilditch and McHill, Nature and Science of Sleep, 2019.
- Effects of using a snooze alarm on sleep inertia after morning awakening. Ogawa and colleagues, Journal of Physiological Anthropology, 2022.