There are nights when I climb into bed perfectly comfortable, and a few hours later I’m kicking off the covers. Then there are other nights when I wake up looking for the blanket I tossed aside earlier. Room temperature obviously plays a part, but our bodies are changing temperature throughout the night too, which helps explain why sleeping comfortably can sometimes feel like a moving target.
Your sleeping body temperature naturally rises and falls as part of your normal sleep-wake cycle. In general, your body begins cooling down as bedtime approaches, stays cooler during the night, and gradually starts warming again as morning gets closer. That change is part of your circadian rhythm, the internal clock that helps regulate when you feel sleepy and when you feel more alert.
Of course, that does not mean everyone experiences nighttime temperature the same way. Bedding, pajamas, room temperature, humidity, hormones, your mattress, and even whether someone else is sleeping beside you can all affect how warm or cold you feel during the night.
Your Body Starts Cooling Down Before You Fall Asleep
One of the more interesting things about sleep is that the process begins before you actually fall asleep. As evening approaches, your body starts preparing for rest, and part of that process includes a gradual drop in core body temperature. Your body releases some heat through the skin, especially through areas such as your hands and feet, which is one reason getting warm and comfortable before bed can make you feel relaxed even though your internal temperature is beginning to fall.
This temperature pattern is closely connected to your circadian rhythm. The National Heart, Lung, and Blood Institute explains that your internal body clock helps regulate your sleep-wake cycle along with other daily biological processes. Once you are asleep, your core temperature generally stays lower for much of the night before beginning to rise again as morning approaches.
Most of us never notice any of this happening. We simply notice the results when we suddenly feel too hot, too cold, or much more comfortable after adjusting the blankets.
Why You Sometimes Wake Up Hot
Waking up hot does not necessarily mean anything unusual is happening. Sometimes the explanation is as simple as a bedroom that became warmer overnight, heavy bedding, pajamas that trap heat, or a mattress that holds onto warmth. Anyone who shares a bed also knows another person can basically become a human space heater.
Several small things can add up during the night:
- Heavy comforters or multiple blankets
- Flannel or non-breathable pajamas
- A warm bedroom
- Mattresses or toppers that retain heat
- Sleeping next to another person or pet
- Seasonal changes in humidity and temperature
Hormonal changes can also affect how warm or cool someone feels at night. That is one reason sleeping comfortably sometimes requires a little experimenting rather than simply setting the thermostat to one supposedly perfect temperature and expecting it to work every night.
Why You May Feel Cold During the Night
The opposite can happen just as easily. Because your core body temperature naturally drops while you sleep, a room that felt perfectly comfortable when you went to bed may feel noticeably cooler several hours later. If the air conditioner is running, a ceiling fan is on, or you kicked off your blanket while you were asleep, you might wake up feeling much colder than you expected.
I find that layering makes more sense than trying to find one blanket that is perfect all night long. It is much easier to pull up a light blanket or push it aside than spend the night alternating between too warm and too cold. Lightweight layers also give you more flexibility when the temperature outside changes from one season to the next.
Cold feet can be especially annoying when you are trying to settle down. Interestingly, warming your hands and feet can help your body release heat from its core, which is one reason a warm bath, cozy socks, or simply getting comfortable under the covers can make you start feeling sleepy.
What Is the Best Bedroom Temperature for Sleep?
This is usually where articles give one exact temperature and make it sound like everyone should immediately adjust the thermostat, but real life is not quite that simple. Many sleep experts recommend keeping the bedroom cool, often somewhere around the mid-60s Fahrenheit for adults, and the Sleep Foundation lists about 65°F as a common starting point. Personal preference still matters, though, because bedding, pajamas, humidity, and even whether you share the bed can all change what feels comfortable.
Someone who loves sleeping under a heavy comforter may prefer a cooler room, while someone using lightweight bedding might be perfectly comfortable with the thermostat set a little higher. I think that is a much more realistic way to look at it than trying to hit one supposedly perfect number. The goal is simply to create a room where your body can cool naturally without leaving you shivering or waking up overheated.
If you tend to wake up hot, lowering the temperature slightly or switching to lighter bedding may make more sense than making a drastic change. If you wake up cold, an extra lightweight layer might be all you need.
Your Bedding Can Make a Big Difference
Changing the thermostat is not always the easiest solution, especially when two people sharing a bedroom have very different ideas about what feels comfortable. Bedding gives you much more control over your own sleeping space, and sometimes a simple change in sheets or blankets makes a bigger difference than changing the room temperature.
Breathable fabrics such as cotton and linen usually allow more airflow than heavier materials designed to trap warmth. If overheating is a regular problem, it may be worth paying attention to what is directly touching your body before deciding the entire bedroom needs to be colder. A lightweight comforter or layered blankets can also make it easier to adjust your temperature during the night without fully waking up.
The same idea applies to pajamas. Heavy sleepwear may feel cozy when you first get into bed but become uncomfortable a few hours later. Lightweight, breathable pajamas tend to work better if you are someone who regularly wakes up feeling too warm.
Your Mattress May Be Part of the Problem
Bedding gets a lot of attention, but your mattress can also affect how warm you feel while sleeping. Some mattress materials hold onto body heat more than others, and that warmth can build during the night even when the bedroom itself feels fairly cool.
Memory foam is probably the material most often associated with heat retention, although newer mattresses frequently include cooling layers, gel, or other materials designed to improve airflow. Mattress protectors and thick toppers can also change how much heat becomes trapped underneath you.
Before replacing a mattress simply because you sleep hot, it makes sense to look at the easier things first. Lighter sheets, breathable pajamas, fewer layers, or a thinner mattress protector may be enough to make the bed feel more comfortable.
Humidity Can Change How the Room Feels
Temperature is only part of the comfort equation. Humidity can make the same bedroom temperature feel completely different from one night to another, especially during warmer months.
When the air is humid, sweat does not evaporate as efficiently, which can make you feel warmer and stickier even if the thermostat has not changed. On the other hand, very dry air can sometimes make a cool room feel even less comfortable.
This is one reason focusing only on the number displayed on the thermostat does not always solve the problem. The overall environment matters just as much as the actual temperature.
Temperature Is Only One Piece of Better Sleep
A comfortable bedroom can certainly make sleeping easier, but temperature is only one part of a good sleep environment. A dark room, less noise, and a reasonably consistent bedtime can all make it easier for your body to settle into its natural nighttime routine.
Sleep also affects much more than whether you feel tired the next morning. There are several reasons good sleep is important for your health, including concentration, energy, and how well you function throughout the day.
Poor sleep can also spill over into the rest of the day, affecting energy, appetite, and even the kinds of foods that sound appealing when you are tired. There is a real connection between sleep deprivation and diet, which is one more reason consistent, restful sleep matters.
Finding the Sleep Temperature That Works for You
I do not think there is much value in obsessing over whether your bedroom is exactly 65, 67, or 69 degrees. What matters more is noticing how you actually feel when you wake up and making small changes from there.
If you regularly wake up sweaty, try removing one layer, switching to lighter bedding, changing your pajamas, or lowering the thermostat slightly. If you wake up cold, adding a light blanket that can easily be pulled up during the night may work better than heating the entire room. Give each change a few nights before deciding whether it made a difference.
Your sleeping body temperature is going to change throughout the night no matter what you do. The goal is not to control every degree, but to create a sleep environment that works with those natural changes instead of making you spend half the night fighting with the covers.