What's Your Caffeine Cutoff

Getting enough sleep is one of the best things you can do for your brain. Most people need at least 7 hours to think clearly and feel well the next day. But sleeping more than 8 hours can also be harmful.

Scientists have names for these two sleep patterns. Short sleep is when you get fewer than 7 hours. Long sleep is when you get more than 8 hours. The healthy middle is 7 to 8 hours each night.

Research shows clear risks:

• Too little sleep raises your chances of memory loss and thinking problems. Short sleep is linked to 70 to 100% higher odds of dementia and Alzheimer’s disease.
• Too much sleep is risky too. Sleeping longer than 8 hours gives about 1.8 times greater odds of Alzheimer’s disease.
• Both too little and too much sleep change how the brain works. This makes it harder for the brain to send signals, and can hurt memory and attention
  
  This means your brain works best when your sleep is steady and balanced. Here’s how to do it:

• Set an alarm so you get at least 7 hours but no more than 8.
• Test what feels right: 7, 7½, or 8 hours.

References:

Gardiner C, Weakley J, Burke LM, et al. The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep Medicine Reviews. 2023;69(101764):101764. https://doi.org/10.1016/j.smrv.2023.101764

Roehrs T, Roth T. Caffeine: Sleep and daytime sleepiness. Sleep Medicine Reviews. 2008;12(2):153-162. https://doi.org/10.1016/j.smrv.2007.07.004