22 Facts About Sleep That Will Surprise You

We spend about one-third of our time on planet Earth asleep. Until 25 years ago, scientists knew little about this nighttime habit of ours.

Below, sleep disorders specialist Michelle Drerup, PsyD​, shares some curious and fantastic facts about sleep.

1. Research shows that in the days leading up to a full moon, people go to bed later and sleep less, although the reasons are unclear.
2. If it takes you less than five minutes to fall asleep at night, you’re probably sleep-deprived. Ideally, falling asleep should take 10 to 15 minutes.
3. Sea otters hold hands when they sleep so they don’t drift away from each other.
4. Tiredness peaks twice a day: Around 2 a.m. and 2 p.m. for most people. That’s why you’re less alert after lunch.
5. Have trouble waking up on Monday morning? Blame “social jet lag” from your altered weekend sleep schedule.
6. We are the only mammals that willingly delay sleep.
7. Stress, physical or mental illness, living or sleeping arrangements, family history, shift work, diet and exercise habits can all contribute to insomnia.
8. Finding it hard to get out of bed in the morning is a real condition called dysania. It may signal a nutritional deficiency, depression or other problems.
9. Insomnia is not defined by the sleep you lose each night, but by the drowsiness, difficulty concentrating, headaches, irritability and other problems it can cause each day.
10. English bulldogs are the only canines known to experience sleep apnea, a breathing disorder. Their unusual airway anatomy (short snouts and underbites) is likely the reason.
11. Being awake for 16 hours straight decreases your performance as much as if your blood alcohol level were .05% (the legal limit is .08%).
12. In the 17th century, getting up in the middle of the night was normal. People slept in two segments divided by an hour or two of alertness (time for reading, praying, intimacy or socializing with others).
13. Going without sleep is likely to make you hungry as levels of leptin, an appetite-regulating hormone, fall.
14. You’re less likely to have a traffic accident when daylight savings time ends. Statistics show that the extra hour of sleep reduces accidents.
15. One job in early English mill and factory towns was to knock on people’s windows to wake them up for work.
16. Sleeping on the job is less of a problem in Japan. Companies may accept it as a sign of exhaustion from overwork.
17. Some car rental contracts make you promise not to drive on fewer than six hours of sleep.
18. Insomnia is often a normal part of grieving. Taking sleeping pills can disrupt this natural process.
19. Regular exercise usually improves your sleep patterns. Strenuous exercise right before bed may keep you awake.
20. Today, 75% of us dream in color. Before color television, just 15% of us did.
21. Whales and dolphins literally fall half asleep. Each side of their brain takes turns so they can come up for air.
22. One of our biggest sleep distractions is 24-hour internet access.