Why You Have Weird Dreams — & How To Control Them

Maybe this has happened to you: You wake up at night after just a few hours of sleep and find you've been dreaming about the grocery-store run you need to make. The next night, you wake up at 5 a.m. and realize you were just flying through the clouds on the back of your pet woolly mammoth, who was spiriting you to an important business meeting with your childhood best friend. (For example.) This difference in dream wildness may not be random: New evidence supports the idea that the dreams you have later in your sleep cycle are longer and stranger than the dreams you have earlier in the night.

A small study just published in Dreaming offers new insight into "continuity" in dreams, meaning the ways that your waking life influences your dreams, and vice versa. Researchers from the U.K.'s University of Bedfordshire and Leeds Metropolitan University enlisted 16 insomnia-free volunteers (11 female, five male, from 19 to 54 years old) to wear sensors that tracked their eyelid and body movements over two nights of sleep each.

Each participant was woken up four times on the two different nights: between the half-hour and 2-hour marks, between the 2.5 and 4-hour marks, between the 4.5-and 6-hour marks, and between the 6.5- and 8-hour marks. (No word on whether participants were offered free, unlimited coffee the next morning.) The participants audio-recorded what they remembered of their dreams each time they woke up, and in the morning they answered questions that evaluated their dreams' emotional intensity and relatedness to their waking lives. A total of 51 dreams were collected, and late-night dreams were shown to be significantly stranger and less realistic than early-night dreams. Unrealistic waking-life references appeared more frequently in late-night dreams, while references to media that dreamers had consumed were more prevalent early in the sleep cycle.

Most dreams occur during REM sleep, the only kind of sleep during which our cortexes are roughly as active as they are when we're awake. Rapid eye movement (REM) sleep dominates late-night shuteye. And, researchers posit that this type of sleep triggers integration of longer-term memories (which are "stored" throughout your cortex) into your dreams. What's more, during REM sleep, your visual cortex is more active than when you're awake, while your prefrontal lobes — the seat of reasoning — are less active, resulting in visually intense, memory-referential dreams that don't obey real-world logic.

So, what if your dreams are so freaky that you'd like to control what happens in them — a process known as lucid dreaming? Deirdre Barrett, PsyD, author of The Committee of Sleep, offered her tips to Scientific American: First, set the intention. Just before you fall asleep, remind yourself, out loud even, that you'd like to recognize that you are dreaming as you dream. If you are having the same dream over and over again and you'd like to change how it goes, when you're awake, rehearse an alternate ending in your head; imagine and vocalize that ending as you fall asleep. Finally, during the day, get in the habit of reminding yourself that you're awake. It sounds strange, but what will happen is that as you dream, you'll start wondering whether you're dreaming. When you realize you are is when you'll be able to influence the course of that dream. And, if you just can't get the hang of it, you can always watch other people lucid-dream instead.