Your coffee cutoff for a 8 AM alarm
Short answer: stop caffeine by 4:15 PM. If you wake up at 8:00 AM and want 7.5 hours of sleep, get into bed around 12:15 AM. That leaves about 8 hours of coffee time after you wake up. After 4:15 PM, switch to decaf, herbal tea or water.
| Sleep | Bedtime | Cutoff (light) | Cutoff (normal) | Cutoff (hard) |
|---|---|---|---|---|
| 6 hours | 1:45 AM | 7:45 PM | 5:45 PM | 3:45 PM |
| 7.5 hours | 12:15 AM | 6:15 PM | 4:15 PM | 2:15 PM |
| 9 hours | 10:45 PM | 4:45 PM | 2:45 PM | 12:45 PM |
Light, normal and hard describe how strongly caffeine hits you: we stop caffeine 6, 8 or 10 hours before bed. Caffeine has a half-life of roughly five hours, so an afternoon cup is still partly active at bedtime.
Common questions
What time should I stop drinking coffee if I wake up at 8 AM?
Have your last coffee by about 4:15 PM. That's 8 hours before a 12:15 AM bedtime, which gives you 7.5 hours of sleep and 15 minutes to fall asleep.
What time should I go to bed if I wake up at 8 AM?
Aim for 12:15 AM for 7.5 hours of sleep (five 90-minute cycles), 10:45 PM for 9 hours, or 1:45 AM for a short 6-hour night.
Can I have coffee at 5 PM if I wake up at 8 AM?
With a normal sensitivity it's after your 4:15 PM cutoff, so it can push your sleep back. If caffeine barely affects you, your cutoff moves to 6:15 PM, so a 5 PM cup is probably fine.