Hopefully this only applies to British people, but a new study says consistent nightmares as a child may indicate a greater likelihood of mental problems as an adult. According to the study, only 37% of test subjects had nightmares several years in a row, and 10% had night terrors, but the nightmare sufferers are three and a half times more likely to have subsequent mental illness issues than the general population, and those with consistent night terrors, twice as likely.

The researchers are quick to point out that having nightmares and even night terrors are common; it’s just when they become persistent that they are problematic. The researchers are unsure why the bad dreams indicate mental illness, but they say the best way to avoid them is to get sufficient, regular sleep.