Exercise right before bed may keep most people from sleeping, but for others, it might be the answer to their insomnia.
While exercising right before bed might hinder sleep, it is often recommended for earlier in the day, particularly when it exposes one to sunlight in the early morning hours.
"In the broad sense, exercise is generally good for sleep," said Basner, adding that exercise during the day is often recommended for people with insomnia. "People really need to experiment and see what's best for them."
Gehrman explained that for many, exercise can hinder sleep because it elevates body temperature, which remains higher for several hours.
But, he said, he has one patient with insomnia who uses 11 p.m. swims to help him fall asleep.
"Some people deviate from the normal pattern," he said.
Does having sex before bed allow people to destress and fall asleep easier, or does it simply make them more alert and less able to sleep?
"I'm not aware of any studies that have looked at that," said Gehrman, reflecting how a number of sleep researchers responded to this question.
Researchers had a number of explanations for how sex might affect sleep. Sex may help some sleep by calming them down before bedtime. Alternately, it may keep them awake, particularly if it is not enjoyable.
"I'm not sure there's a lot of evidence to answer that well," said Basner. As with exercise, "I guess people have to experiment on their own."
No foods have ever been linked to bad dreams.
But, Basner said, that doesn't mean a large meal at bedtime won't hinder sleep, as it fills up stomach, meaning blood has to work to help digest the food rather than flow to other organs.
"Certainly it's a bad idea," he said.
The primary effect, he and other researchers said, was likely to be reflux and discomfort at bedtime.
"I don't think it's true you're risking nightmares so much, you're just not able to sleep as well," said Basner.
But researchers doubted whether specific foods could bring on bad dreams.
"Only if it gives you a tummyache," said Cartwright.
Warm milk, and turkey, have gained plenty of myth mileage because they contain the amino acid tryptophan.
"[Warm milk] might be relaxing, but here's probably nothing chemically that's going to make you fall asleep," said Gehrman.
While tryptophan may be used as a sleep aid pharmaceutically, its power in food can be severely reduced. Even in pill form, tryptophan is not as strong as sleep aids such as Benadryl.
Avidan noted that the strongest links between foods and sleep come better-known substances, with smoking, alcohol and caffeine all having disruptive effects on sleep patterns.
Myth Based on a Fact
As you may have suspected, the scientific literature on sleep does not show any evidence that Freddy Krueger can kill you by invading your dreams. However, the idea for the film seems to come from a real-life phenomenon linked to a real-life murderous villain.
In the 1970s, millions of Cambodians were killed by Pol Pot's Khmer Rouge regime. Some refugees fled to the United States, and it was observed that some young men were reluctant to sleep -- and some died from heart attacks while sleeping.