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How to sleep in the heat (8/15/11)

August 15, 2011

It’s Hot Out There

There are riots, financial meltdowns, fiscal crises.  It’s hot out there.

Global climate change may be a myth to some non-scientists, but most models of  global weather predict greater volatility – more extreme hot weather and cold, more floods and hurricanes – for a long time to come.

And then there’s summer.

Summer here in south Florida is normally hot and long.  This year it’s been hot in many places.  Record temperatures have been set throughout the US – and the world.  Newark hit 108 degrees the other week; Dallas baked above 100 degrees for  40 days. Droughts bedevil farmers and turn the land to dust.

So people try to sleep in the heat.  When there’s no air conditioning, that’s difficult. It’s often difficult even when there is air conditioning.

There are many reasons people don’t sleep well in hot weather – and many things to try when they do.

Why You Can’t Sleep When It’s Hot

Putting people in environments above 80 degrees Fahrenheit (26.7 degrees Celsius) has long been known to make sleep difficult.  Many people have trouble sleeping when it’s above 75 degrees.  Sometimes it’s because of dehydration brought on by the heat of the day.

More commonly the reason is REM sleep.

REM is effectively a different state of consciousness, where the body helps rebuild and rework memory, loses all muscle tone except that needed to breathe, and aborts inner temperature controls – just like when you were newly born.

So in REM, which is normally 20-25% of sleep, your body temperature gradually becomes whatever is outside.

If it’s hot you wake up.  Hot temperatures may also cause many to sweat, particularly women already suffering from hot flashes.

When people don’t sleep they get irritable.  They don’t remember as well.  Their mood is lower.  Their immunity is less robust.

So sleep loss is one reason among many why there is much written throughout history of  “long hot summers,” whether it’s the present Arab “Awakening” or the recent English riots.  The actual behavioral literature is much more equivocal as to weather’s effect on crime, and political upheaval.  Yet when people are hot and don’t sleep well, they don’t feel well – and sometimes do something interesting about it.

So what can you do to sleep well when it’s hot?  Here are a few ideas:

  1. If you can afford it, keep the temperature at night cool.  People sleep better in cooler temperatures down to rather low levels; many find temps in the low 70’s adequate to sleep better at night.
  2. If you wake in the middle of the night, cool the temperature one or two degrees. David Avery and others have shown that lowering temperature often provokes falls into REM sleep at night, and provides better overall quality of sleep.
  3. If you are having trouble sleeping through the night, consider a hot bath ending about 30 minutes before you go to sleep – a both hot enough to raise your spinal cord temperature sufficiently to sweat.  The cooling that occurs after sweating apparently acts as a sleep gate that tells the brain to sleep more continually – with more deep and REM sleep than normal.  Hot baths produce a dose response curve – demonstrating greater effect the closer the time you go to sleep. Bathing a half hour before slumber should allow you to get over the “after sweat” and get cool enough to fall asleep readily.
  4. If there’s no air-conditioning, consider a fan.  Cooling air helps us sleep, as does the rhythmic sound of the fan..  Placing ice cubes in a tub next to your bed may also cool the air rushing onto you, cooling the temperature yet more (
  5. When it’s hot, wear as little clothing and use as little bed linen as you find comfortable.
  6. For those without air conditioning or fans, things can be really tough.  Get as much cross ventilation as you can, place your mattress or bed arrangement close to the ground (hot air rises – not just in politics.)  Some may try a cooling, wet T shirt, but for many this is mainly psychological in effect.
  7. Hydrate during the day.  An important but often overlooked factor in poor rest is the dehydration and minor heat stroke that people frequently get during the hot days.

Bottom Line:

It’s harder to sleep in the heat.  But if you know what you’re doing and make sensible adjustments in bed environment and temperature, sleep in summer can be deep and satisfying.

And remember what you do during the day affects the night.  Moving in the sun, particularly in the morning, can still help you sleep at night.  Yet you need to wear the proper clothing – covering everything up, as they do in the desert – so your sweat can cool your body rather than the atmosphere.

And, yes, wear a hat. It pays in multiple ways to keep cool – all through the summer.
Rest, sleep, Sarasota Sleep Doctor, well-being, regeneration, longevity, body clocks, insomnia, sleep disorders, the rest doctor, matthew edlund, the power of rest, the body clock, psychology today, huffington post, redbook, longboat key news

One Comment leave one →
  1. s. west permalink
    August 15, 2011 11:51 AM

    Yes, that is all good advice. I wonder if a certain type of material for sleeping on is preferable to cotton? Thanks.

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