How a hot shower can help you get 90 minutes of deep sleep

Regardless of how many hours we sleep at night, spending sufficient time in deep sleep is the foundation of optimal performance and health.

Over the last weeks, I’ve explained how to set up both factors of our wake and sleep – our circadian rhythm and our adenosine level – to spend 90 minutes each night in that most rejuvenating sleep stage.

I’ve created and shared two simple rules that help you set the three major circadian synchronizers (or “time givers”) while managing your adenosine level accordingly: The 10-10-10 rule on viewing light and the 3-3-3 rule on exercise and nutrition.

Following these rules goes a long way to set your brain and body up for 90 minutes of deep sleep in the first half of the night.

However, life happens. While viewing light usually doesn’t pose a problem, adhering to the 3-3-3 rule can sometimes be challenging. Maybe you’re only able to squeeze in an intense workout at the end of a long day at work. Or perhaps you feel like having a coffee with a friend late in the afternoon – or even a lavish dinner with your spouse at night.

When that happens, all is not lost. There’s a simple way to prepare for a great night of sleep regardless. It works by controlling your body temperature in the evening.

Remember that getting into deep sleep in time requires us to drop our core body temperature early in the night. It might seem counterintuitive, but the quickest way to accomplish that feat is by exposing ourselves to heat.

When we take a hot shower or bath, the hot water triggers our body’s natural cooling mechanism. According to recent sleep science, this works by sending warmer blood from our core outward, shedding heat through our hands and feet. That rebound decrease in thermogenesis (as scientists call it) sends a signal to your body that it’s time to sleep.

The takeaway: Whenever you’ve had an intense workout, coffee or meal late in the day, take a hot shower (or bath) for at least one minute before going to bed. That will allow you to cool down your body, calm down your mind – and set you up for the deep sleep you need.

Pro tip: Using temperature to change your alertness level also works the other way around. If you’re having trouble getting going in the morning, the simplest remedy is ending your (warm) shower by turning the water to as cold as you can safely tolerate for at least one minute. That practice will not only make you much more alert at the moment. When you get out of the cold water, your body will trigger a rebound increase in thermogenesis. That higher body temperature will then make you more alert throughout the morning.

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Until next week,
Christian