Listening to affirmations while you sleep is unlikely to work the way it’s usually sold: studies going back to the 1950s found that people don’t remember words played to them once they are truly asleep. Newer lab studies have found some learning during sleep, but of simple associations or faint traces, not new beliefs. What does have support is the time just before sleep, while you’re still awake, when calmer thoughts and a steady routine can help you drift off.
Can you learn while you sleep?
The idea is old. In the mid-twentieth century it was tested carefully, using brain-wave recordings (EEG) to check whether people were really asleep when the words played.
- In one study, 96 questions and answers were played to sleepers every five minutes. As the brain-wave signs of wakefulness faded, so did people’s ability to respond or remember. Once they were clearly asleep, recall essentially stopped, and the few items remembered mostly lined up with moments of partial waking. The researchers concluded that learning during real sleep was “impractical and probably impossible” (Simon & Emmons, 1956).
- In another, a list of ten words was repeated as many times as possible through an eight-hour night. Afterward, the sleepers did no better than a control group at picking those words out of a longer list (Emmons & Simon, 1956).
- Decades later, people who heard word pairs during REM or light sleep showed no learning on tests of unconscious (implicit) memory, unlike people who heard them awake. The few words that were remembered had been followed by the sleeper waking up (Wood et al., 1992).
The pattern was consistent: if you remember it, you were probably awake when you heard it.
What newer research has found
Modern studies have found that the sleeping brain is not completely shut off from learning. But look closely at what was learned.
- Simple associations. Sleepers who heard tones paired with pleasant or unpleasant smells later sniffed differently when they heard the tones alone, at night and the next day, without knowing they had learned anything (Arzi et al., 2012). In a follow-up with people who wanted to quit smoking, pairing cigarette smell with an unpleasant smell during sleep cut the number of cigarettes they smoked over the following days. The same pairing while awake did not (Arzi et al., 2014).
- Sounds, with a twist. Repeated noise patterns played during REM or light sleep were recognized better after waking. The same exposure during deep sleep made people recognize them worse (Andrillon et al., 2017).
- Faint traces of words. People who classified spoken words as they drifted into sleep didn’t remember those words on waking and couldn’t tell them apart from new ones, though subtle measures showed an implicit trace (Andrillon & Kouider, 2016).
- New word links, under tight conditions. During a nap, sleepers heard pairs of made-up words and real words. When the second word happened to land on the peak of a slow brain wave, people later showed signs of having linked the pair, though only on an implicit, forced-choice test (Züst et al., 2019).
None of these studies tested affirmations, beliefs or self-esteem. The learning they found was simple, faint or dependent on precise timing with brain waves, which an all-night playlist can’t match.
The one thing sound during sleep can do
There is a well-supported effect, but it works on memories you formed while awake. In “targeted memory reactivation,” people learn something while linked to a sound or cue, then hear the cue quietly during sleep. A meta-analysis of 91 experiments with 2,004 people found that this improved later memory on average, by a small amount, when the cues came during non-REM sleep, but not during REM sleep or while awake (Hu et al., 2020). In one example, replaying Dutch words that people had learned before sleeping helped them recall the German translations the next day (Schreiner & Rasch, 2015).
This is real science, and a major review describes how memory processing in sleep can support problem solving and emotional regulation (Paller, Creery & Schechtman, 2021). But it strengthens what you practiced while awake, in carefully timed lab conditions. It doesn’t install new ideas.
What about subliminal affirmations?
“Subliminal” tracks, with messages too quiet or masked to hear, have been tested directly, although with people awake. In double-blind studies, 237 people used subliminal tapes sold to improve memory or self-esteem for a month. Neither kind worked. People improved a little whichever tape they had, a placebo effect, and over a third believed they had improved in whatever area the label promised (Greenwald et al., 1991).
Can sleep affirmations hurt?
For most people, quiet audio is probably harmless. But sound can work against sleep. Noise is known to disturb sleep and cause daytime sleepiness (Basner et al., 2014), and health guidance recommends keeping your bedroom quiet, cool and dark (NHLBI, 2022). A voice playing all night doesn’t fit that advice. If you listen at bedtime, use a sleep timer.
What actually helps at bedtime
The minutes before sleep are where words can do some good, because you’re still awake to hear them. Unwanted thoughts and worries are a common complaint among people who can’t get to sleep (Harvey & Payne, 2002), and several simple techniques have evidence behind them:
- Write a to-do list. In a sleep-lab study, people who spent five minutes writing a specific to-do list for the coming days fell asleep faster than people who wrote about tasks they had already finished. The more specific the list, the faster they fell asleep (Scullin et al., 2018).
- Give your mind a calm picture. People with insomnia who were taught to fill their minds with an engaging, detailed imagined scene fell asleep faster and had fewer distressing thoughts at bedtime than people given no instructions (Harvey & Payne, 2002).
- Try gratitude or a worry plan. In a small pilot study, students whose racing thoughts kept them up tried one of three short techniques (planning around worries, calming imagery, or a gratitude exercise). Each one reduced worry and arousal at bedtime and improved sleep compared with the week before (Digdon & Koble, 2011).
- Listen to calm music. A review of 13 trials found moderate-certainty evidence that listening to music improved how well adults with insomnia felt they slept, though it was less clear for objective sleep measures (Jespersen et al., 2022).
- Keep a routine. Going to bed and getting up at the same time, using the hour before bed for quiet time, and trying relaxation techniques are all standard advice (NHLBI, 2022).
Bedtime affirmations fit into this as a calm, deliberate wind-down while you’re still awake, not as overnight learning.
In practice: a bedtime routine with affirmations
- Lights low, screen down, about an hour before sleep if you can.
- Five minutes on tomorrow. Write down what you need to do, as specifically as you can, so your mind doesn’t have to hold it.
- Three to five calm lines, said or heard while you’re awake. Keep them gentle and believable: “I’ve done enough for today.” “Tomorrow’s list is written down; I can let it rest.” “Rest still counts, even if sleep takes a while.”
- A sleep timer, so any audio stops as you drift off.
- If worries come back, return to one detailed, calm picture rather than arguing with them.
You’ll find more lines like these in our sleep affirmations.
If worry keeps you awake most nights, or poor sleep goes on for weeks, talk to a doctor. Bedtime affirmations can help you wind down, but they aren’t a treatment for insomnia or anxiety. If you’re struggling or thinking about harming yourself, you can call or text 988 in the US (Suicide & Crisis Lifeline), or find a helpline in your country at findahelpline.com.
The short version
- Words played during real sleep aren’t remembered, according to studies going back to the 1950s.
- Newer lab studies found limited sleep learning, of simple associations or faint traces, under tightly controlled conditions. None tested affirmations.
- Sound during sleep can strengthen memories formed while awake, but that’s different from absorbing new beliefs.
- The best use of affirmations at night is while you’re awake, as part of a calm routine, with a timer so the audio doesn’t disturb your sleep.