Sleep Calculator
Find out what time to go to bed or when to wake up, based on your body's natural 90-minute sleep cycles.
What time should I go to bed?
Enter your wake-up time and we'll show you the best bedtimes to wake up feeling refreshed.
We add 15 minutes for falling asleep, then calculate backwards in 90-minute cycles.
How sleep cycles work
Your brain doesn't simply switch off when you fall asleep. It cycles through four stages every 90 minutes or so, and each one does something different for your body and mind.
Light sleep
This is the brief transition between wakefulness and sleep. It lasts 1 to 7 minutes. You can be woken easily at this point, and you might experience that familiar falling sensation.
Deeper relaxation
Your heart rate slows, body temperature drops, and brain activity eases. You spend roughly half of your total sleep time here. This stage plays a big part in consolidating memories.
Deep sleep
The most physically restorative stage. Tissue repairs happen here, your immune system gets a boost, and it is very hard to wake you up. Most deep sleep happens in the first half of the night.
Dream sleep
REM stands for Rapid Eye Movement. Your brain is nearly as active as when you are awake. This is when most dreaming happens, and it is essential for emotional processing and creativity. REM periods get longer later in the night, which is why cutting sleep short hits you hardest.
Sleep stage data based on guidelines from the National Sleep Foundation and the American Academy of Sleep Medicine.
How much sleep you need at every age
Sleep needs shift a lot across your lifetime. Babies need more than twice as many hours as adults, and teenagers are somewhere in between.
| Age group | Age range | Recommended hours | Approx. cycles |
|---|---|---|---|
| Newborn | 0-3 months | 14-17 hours | 9-11 |
| Infant | 4-11 months | 12-15 hours | 8-10 |
| Toddler | 1-2 years | 11-14 hours | 7-9 |
| Preschool | 3-5 years | 10-13 hours | 6-8 |
| School-age | 6-12 years | 9-11 hours | 6-7 |
| Teenager | 13-17 years | 8-10 hours | 5-6 |
| Adult | 18-64 years | 7-9 hours | 4-6 |
| Older adult | 65+ years | 7-8 hours | 4-5 |
Recommendations sourced from the National Sleep Foundation and the American Academy of Pediatrics. Individual needs vary based on health, activity, and genetics.
Simple habits that make a real difference
Knowing your ideal bedtime is a good start. What you do in the hours before bed matters just as much.
Stick to a schedule
Going to bed and waking up at the same time every day, including weekends, is the single most effective thing you can do for your sleep quality.
Put your phone down an hour before bed
The blue light from your screen suppresses melatonin, the hormone that makes you sleepy. Even dimmed screens delay sleep. Read more about phones and sleep.
Keep your room cool and dark
Your core body temperature drops when you fall asleep. A cool room (around 16-19°C / 60-67°F) helps that process. Blackout curtains make a bigger difference than most people expect.
Skip caffeine after 2 PM
Caffeine has a half-life of about 5 hours. A coffee at 4 PM still has half its strength in your system at bedtime, making it harder to fall and stay asleep.
Get sunlight in the morning
Natural light within 30 to 60 minutes of waking anchors your body clock. Even on cloudy days, outdoor light is far brighter than indoor lighting and makes a noticeable difference.
Use your bed only for sleep
Working, scrolling, or watching TV in bed trains your brain to stay alert there. Keep the bed for sleep and your brain will start associating it with winding down automatically.
Common questions
Answers to the questions people search for most about sleep timing and duration.