Environmental cues help people reset their internal clocks and can affect sleep cycles. Take the quiz to see how well you know your “time givers.”

Do you know your zeitgebers?

Whether you log a solid seven and a half hours of snooze time or sheet-wrestle all night long depends solely on a funny little word you've likely never heard of.

The term zeitgeber, German for "time giver" or "synchronizer," was coined by biologist Jurgen Aschoff, one of the founders of the field of chronobiology, in a study of the inner rhythms of living organisms.

Zeitgebers are environmental cues that help people reset their internal clocks. Aschoff's work demonstrated that there were both internal biological clocks and external cues that he called zeitgebers that influence the timing of our sleep cycle.

Zeitgebers include such things as natural light, blue light from electronic screens, social interactions, medications, temperature, sound and even when you eat or brush your teeth. These are all external cues that can end up saving—or costing—precious shut-eye.

How knowledgeable are you about the zeitgebers that affect people's sleep cycles?

Q1)  What's the biggest zeitgeber people contend with?

1. Midnight snacks

2. Noisy neighbors

3. Bedroom temperature

4. Light
   
   
   

Q2)  What's most likely to interfere with sleep, if done before bedtime?

1. Eating dinner

2. Exercising

3. Working until bedtime

4. All of the above

Q3)  Why is it so hard to sleep when you're upset?

1. Because your adrenaline is pumping

2. Because you had a screaming match with your spouse

3. Because disturbing social events mess with your sleep cycle

4. Because your heart rate is faster

Q4)  What can you do to make the most beneficial impact on your zeitgebers?

1. Go to bed at the same time every day.

2. Stick to a regular routine.

3. Watch a movie at least once a week.

4. Eat breakfast every morning.

Q5)  What's the optimum sleeping temperature for the bedroom?

1. 60 to 68 degrees

2. 68 to 72 degrees

3. 72 to 76 degrees

4. above 76 degrees

ANSWERS

1. D. Light.The zeitgeber with the biggest impact on our sleep cycle is light. It's not just natural light that affects our sleep, but also unnatural, man-made lights and blue lights from electronics. One of the single best things you can do for good sleep is to eliminate light. Use darkening window treatments, purge electronic screens from the bedroom and replace glowing alarm clocks that cast a light haze over your room while sleeping.
   
   

2. D. All of the above, according to fitness guru Mark Sisson.Intense exercise right before bed may suppress melatonin and delay the sleep cycle. Eating also appears to suppress melatonin secretion. Being social and working during the day, but having quiet time before bed, signals to your body that night time is for rest. Flip the script by working late into the night and your body won't get the cue that it's time for sleep.
   
   

3. C. Because disturbing social events mess with your sleep cycle.Social cues are a zeitgeber. Throw them off with a disruptive event like a death, breakup, huge fight with your mother, or even a minor disturbance like a disagreement at work, and your sleep cycle may get out of whack. The Social Rhythm Stability Hypothesis proposes that upsetting social events like these disrupt your biological circadian rhythm. In other words, yes, you can't sleep when big drama goes down.
   
   

4. B. Stick to a regular routine. In a study in the journal Sleep, elderly nursing home residents who had a highly regular lifestyle (a regular life routine, which they mostly stick to) where they sleep, eat, exercise and are social at similar times daily, amplified their zeitgeber effects and slept more soundly.
   
   

5. A. 60 to 68 degrees. By dialing down body temperature at night, people have less insomnia. In fact, temperatures that fall too far above or below 60-68 degrees can cause restlessness. When you go to sleep your body's internal temperature goes down so if you're too hot or too cold, the body struggles to achieve the internal temperature that helps induce sleep.

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ABOUT THE AUTHOR

Jennifer Nelson is a Florida-based health writer who writes about all things sleep hygiene. She writes for The National Sleep Foundation, Phillips, Tom's Guide, Southern Living, Health, AARP and others.