Neuro Athletes,

If you’re reading this I hope your week is off to a great start and you are ready to get into the question I get asked most about sleep.

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It’s crazy that we’re living in a day and age where we now have a category of fitness that is dedicated to sleep. When it comes to quality sleep there are a few things that people get wrong and one of them is temperature.

It turns out that your body needs to drop its core temperature by about 2 to 3 degrees Fahrenheit to initiate sleep and then to stay asleep. And it's the reason you will always find it easier to fall asleep in a room that's too cold than too hot. So aim for a bedroom temperature of around 65 degrees or about 18 degrees Celsius.

So let’s talk about sleep and temperature control in today’s newsletter.

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Primer

Core body temperature follows a circadian rhythm, meaning that it rises and falls across a 24 hour cycle.

It’s widely accepted that a drop in core body temperature is a signal for our bodies to prepare for sleep - this is a deeply ingrained characteristic that is common across a number of mammals.

The reasons underpinning the alignment of core temperature changes to the day/night cycle are rather complex. In the run up to sleep, the body’s temperature starts to fall and this is linked to a reduction in the time it takes to fall asleep.

During the course of the night, there is a drop in core temperature of about 1°C, with the lowest body temperature occurring in the early morning.

Conversely, increases in core temperature during sleep appear to promote waking. About two hours before we wake, our core body temperature begins to rise and it continues to rise throughout the day, peaking in the early evening.

It has also been observed that people living with insomnia have a core body temperature rise and fall that isn’t in line with their chosen bed time.

For core temperature changes to happen, our bodies need to be able to retain or lose heat effectively.

Humans do this via the skin, which has a network of blood vessels running under it. Blood vessels open up (a process called vasodilation) or narrow down (a process called vasoconstriction) depending on whether core body temperature needs to decrease or increase.

If a core body temperature decrease is required, heat can be lost through the peripheral skin (the skin covering the arms, hands, legs and feet).

In this way, the skin acts as a ‘radiator’ for excess body heat. While this may sound out of place in an article about sleep, we can use this feature of our bodies to get a better night’s sleep.

FIGURE: Thermoregulation is important for human sleep. (A) Humans use bedding to form warm microclimates during sleep. These activate central hypothalamic mechanisms to induce sleep and peripheral vasodilation. (B) Distal-to-proximal gradient and core temperature decline predict sleep onset (adapted from Krauchi et al., 2000).

Best Temperature to Sleep At

The consensus among scientists is that the temperature in the bedroom should be around 16-18°C. This allows you to lose body heat throughout the night, which is essential for good sleep.

The room temperature is not the only factor you need to consider. The temperature under your bedclothes is also important. This needs to be roughly between 27 and 32°C to ensure good sleep.

The humidity of the air is also important. High humidity values, particularly in hot climates, have a negative impact on deep sleep and increase wakefulness.

It’s also worth noting that your temperature preference is also affected by variables such as the time of year and your sex. We can tolerate higher sleep temperatures during summer more than winter and women prefer a slightly higher bed temperature than men.

It can be useful to experiment with different pre-sleep activities, bedding and clothing materials, as well as room humidity values, to determine what works for you.

Tools to help with Temperature Control

1. The “Warm Bath Effect” - Immersion in hot water prior to, but not immediately before, the sleep period decreases sleep latency and increases sleep depth. This is the known as the ‘Warm Bath Effect’. In fact, warming for up to 4 h, between 1 and 8 h before to going to bed, increases slow wave sleep (SWS), increases NREM consolidation and decreases REM sleep. This effect embodies a key connection between temperature and sleep.

2. Eight Sleep Mattress- With Temperature Autopilot, the Pod adjusts your sleeping temperature to your individual patterns, supporting the flow of each sleep cycle to maximize recovery. Temperature on each side of the bed can range from as low as 55℉ to as high as 110℉.

This Week On The Neuro Experience Podcast

PART I 

• The 6 pillars of hormone optimisation 

• What genetic tests tell us about hormones 

• Sleep and hormone production 

PART II

• Female hormone optimisation 

• Hormones and fertility 

• Hormone optimisation for female athletes 

• Metabolic syndrome in women 

• The menopausal women- what is happening and the link between Alzheimers Disease 

• What tests women should be ordering

PART III 

• Male hormone optimisation

• Low sperm count and low testosterone levels 

• Fertility - sperm count 

• Why men take testosterone and is this leading to cancer?

• Sleep optimisation