Sleep Science
How many hours of sleep do most adults need each night?
7–9 hours
True or False: You can train your body to function well on 4–5 hours of sleep.
False — your brain still suffers even if you feel “used to it.”
Which animal can sleep with only half of its brain at a time?
Dolphins
True or False: Everyone dreams, even if they don’t remember it.
True
True or False: Going to bed at the same time every night helps you sleep better.
True
True or False: Only humans can experience REM sleep.
Many mammals and some birds also experience REM sleep.
What’s the world record for the longest anyone has stayed awake?
11 days
What’s the most common emotion people experience in dreams?
Anxiety
Roughly how long does one full sleep cycle last for most people?
90 Minutes
Some people claim short naps can boost focus and alertness. Is that true — and what’s the ideal nap length?
Yes — naps of 10–30 minutes can boost alertness and memory without entering deep sleep or causing grogginess.
What percentage of your dreams do you forget within five minutes of waking up?
95%
About how many dreams does the average person have per night?
4 to 6