Want to fall asleep fast and wake with lots of energy? This is the simple 'temperature pre-loading' hack a sleep expert recommends

When it comes to sleep, your internal clock sometimes needs a nudge in the right direction — similar to an alarm clock, only instead of waking you up, it tells you it's time to drift off. Sam Sadighi, sleep expert at GetLaidBeds, has just the trick.

She describes it as "temperature pre-loading" but you probably know it best as a warm shower in the evening. Yes, it really is that simple as this habit shifts your internal clock into the 'sleep' part of the 'sleep-wake' cycle, essentially tricking your body into winding down.

As Sadighi explains, "temperature pre-loading" can help you fall asleep faster and wake up feeling fresher. And it's not the only way to pull the wool over the eyes of your body clock.

Key take-aways: At a glance

• A warm shower causes a subsequent drop in your core temperature, something your body clock recognizes as a signal to sleep
• Due to this temperature drop, your body moves into the 'wind-down' phase of the sleep-wake cycle, helping you to fall asleep faster
• A warm evening shower can also helps you to sleep deeper, so you have more energy in the morning
• Aim for a water temperature of 104-108.5°F / 40-42.5°C
• It's a good way to help you fall asleep faster when you want an early night — something the experts describe as a "zeitgeber" or time-giver
• Other time-givers include dimming the lights, lowering your music and have a small snack of complex carbohydrates

Why a warm shower helps you sleep

"Taking a hot bath or shower around 90 minutes before bed triggers a rapid drop in core temperature afterwards — mimicking the body’s natural sleep signals," says Sadighi, founder of Easy Sleep Solutions.

It's deceptively simple but a habit almost anyone can follow that has some big benefits (we'll dive into those below.)

Even Elvis and Been Caught Stealing Star, Austin Butler, is getting in on the warm shower before bed action, as he explains to Drew Barrymore below...

This all goes back to our ancient ancestors. Our circadian rhythms were trained to recognize cool evenings as a cue that sleep is coming.

Nowadays, with ample indoor heating, that natural signal isn't always around — a warm shower and subsequent cooling are the next best things.

As a result, your internal clock knows it's bedtime and you can enjoy improved sleep latency. In other words, you fall asleep faster.

For this reason Sadighi describes temperature as a "zeitgeber" or time-giver, and recommends using it to trick your body into an early night whenever you want to get ahead of jet lag, bank some sleep, or even beat a clock change.

The clear signaling of a warm shower doesn't just help you fall asleep, it can help you stay asleep as well.

"When we use temperature pre-loading, such as a hot bath, we aren't just shifting the timing, we are improving sleep efficiency," explains Sadighi.

As a result, you're more likely to wake up feeling fresh and full of energy.

3 other ways to trick your body into going to sleep early

A warm shower isn't the only way to send your circadian rhythm a nudge that it's time to sleep. If you're tired of lying awake after climbing into bed or you find light, fragmented sleep leaves you groggy in the morning, try these expert tips...

1. The 'Amber Dusk' method

Like temperature, light is another important indicator to your circadian rhythms — when it gets dark, your body knows to sleep.

However, indoor lighting and bright screens in the evening means it might not be until you get into bed and turn the lights off that your internal clock gets this signal.

To counter this, Sadighi recommends a simple evening switch.

"Two hours before your bedtime, switch off all overhead lights and use only lamps with warm-toned (amber or red) bulbs," Sadighi suggests, a trick she calls the "amber dusk method."

"This mimics the natural shift in the light spectrum at sunset, triggering the brain’s pineal gland to start secreting melatonin earlier than it would under harsh LED 'daylight' bulbs," she explains.

2. Have a simple snack

Sadighi notes that a "pre-sleep carb micro-dose" can help you fall asleep faster.

"A small serving of complex carbohydrates, such as a small oatcake or a few walnuts, about 90 minutes before bed can be helpful," she advises. "This promotes the uptake of tryptophan, which is the precursor to serotonin and melatonin, effectively 'pre-loading' the chemical machinery needed for sleep."

You don't want to eat too close to bedtime (or too heavy a meal) as digestion keeps the body awake, but a quick healthy snack can be sleep friendly.

3. 'Acoustic fading'

'Tricking' your body clock into thinking it's bedtime involves recreating the conditions you'd expect to find in your bedroom. So that's cool, dark... and quiet.

"Start reducing the volume of your environment an hour before bed," advises Sadighi.

During this "auditory fading" she recommends switching upbeat music and loud TVs for something "calmer" (and quieter.)

"This reduces auditory cortisol spikes and signals to the nervous system that the 'survival' part of the day is over," she says.

Now that you're sat in the dim lights, feeling comfortably cool and listening to calm sounds, your circadian rhythm will assume it's time to fall asleep — and should respond in kind.

How 'zeitgebers' benefits your sleep

1. Front-loads deep sleep

During the night the body cycles through numerous sleep stages, with deep sleep a key stage for recovery and restoration (it's also the phase that's hardest to wake up from.)

Showering before bed helps move deep sleep up the pecking order, ensuring you get enough of this vital stage.

"By forcing that rapid core temperature drop, you typically transition into Stage 3 (deep or slow wave sleep) more quickly," explains Sadighi. "This 'front-loads' your physical recovery for the night."

2. Less fragmented sleep

"If done correctly, the wind-down doesn't just make you sleep earlier, it makes the sleep denser," says Sadighi.

Frequent night time awakenings, or fragmented sleep, prevent your body from moving from stage to stage — you might find yourself stuck in a cycle of light sleep.

But showering before bed can reduce fragmentation for overall higher quality sleep.

"You’re less likely to have fragmented sleep because your body is firmly 'locked' into a cooling cycle," explains Sadighi, "which is the biological requirement for staying asleep.”

3. Learning good sleep habits

Having a consistent wind-down routine is one of the best ways to ensure good sleep quality, as by following the same steps before bed, your internal clock recognizes the cues to sleep.

So when you combine the temperature drop of a warm shower with the circadian-friendly repetition of routine, you have the ideal signal for sleep. And don't forget to keep your bedroom at the optimal temperature for sleep (around 65 to 70°F.)

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