晚睡強迫癥: 你睡不著的8個原因

Every once in a while you have a bad night's sleep and you know exactly why: You found yourself at the coffee maker at 4 p.m. or there were sirens blaring outside your window all night or maybe your allergies are killing you. But more often than not the reasons behind your less-than-satisfactory slumber remain a mystery and you slog through the day with the unpleasant memory of your alarm clock's siren close at hand.

We're shining a light on some of the most surprising reasons you can't sleep below. Some of them you can't control, but some of them require only the tiniest of tweaks to help you hit the hay in no time.

We've all been tempted to spend some extra time in bed on a Saturday or Sunday morning (or both, whoops!), but experts say that sleeping late on the weekend (and staying up late, too) can be a bad idea -- for reasons other than productivity. Adjusting your wakeup time can throw off your biological rhythms so drastically that your body feels like it traveled across time zones, and when it comes time to drift off Sunday night, this so-called social jet lag likely won't let you fall asleep without a fight.

No, you're not turning into a werewolf. But the lunar cycle does seem to have some effect on our sleep, at least according to a small study. Researchers found that during the nights around a full moon, people get less deep sleep, less total sleep and took about five extra minutes to fall asleep.

You might think you know what makes for a cozy bedroom, but there's actual research examining optimal sleeping temperature. Generally, the sweet spot is somewhere between 60 and 67 degrees Fahrenheit, Dr. Christopher Winter wrote in a recent blog for HuffPost, with temps below 54 or above 75 deemed disruptive to your slumber.

Even if you've set the thermostat correctly, some people are just disposed to having colder than comfortable extremities. But this can become a problem at bedtime, since warm hands and feet are part of a delicate thermoregulatory dance that seems to predict how quickly you'll fall asleep, according to a 1999 study. Speed up the process by pulling on a pair of clean socks before climbing into bed.

Yes, you want your sleep sanctuary to be calm and quiet, but complete silence can lead to problems. If your room is too quiet, every little "inconsistency of sound" becomes that much more evident and disruptive, Thomas Roth, Ph.D., director of the Sleep Disorders and Research Center at Henry Ford Hospital in Detroit, told Prevention. A white-noise machine can help!

You may be too proud to admit it (even to yourself), but try to be completely honest for a minute: Are you afraid of the dark? Fear of the dark could actually be messing with your shut-eye. In research presented at the 2012 SLEEP conference, people who reported themselves to be "bad sleepers" were found to get more anxious and more easily startled by noises once the lights went off than people who considered themselves "good sleepers", MSN reported. The researchers posited that bedtime anxiety that's often chalked up to knowing a night of fitful sleep awaits may actually be due to a legitimate and untreated phobia.

It's been a long day (or week) and you're feeling stretched to your limits. All you want to do is get into your bed, and you practically have to drag yourself into it. But despite that overwhelming exhaustion, you find yourself annoyed while counting sheep. What gives? "There's actually a big difference between being exhausted and being sleepy," Roth told WebMD. Your body is still on high-alert, even though you can hardly carry on, whether it's because of stress or physical activity. Long story short, rushing to bed doesn't equate to rushing to sleep. No matter how exhausted you feel, it's a good idea to wind down calmly and quietly first.

We know, we know -- you love to snuggle. But allowing a pet in the bed is asking for trouble falling asleep. Every time Fluffy makes a move or a sound, you'll toss and turn right along with her, not to mention she drags with her allergy-triggering animal dander that you're better off keeping outside the bedroom.

And it's not just furry friends that cause problems. Sharing a bed with a partner who tosses and turns or kicks or snores can give you just as much trouble falling asleep. One study found that when sharing a bed, couples experience 50 percent more sleep disturbances than when sleeping solo, the BBC reported. Separate beds may be catching on -- a recent report from Toronto found that 30 to 40 percent of couples sleep apart.