Changes in your temperature reflect your body’s ability to turn up the heat or cool things down to maintain your ideal thermostat. Your body has its own plan for temperature following your circadian rhythm to cool you down for sleep and warm you up for the day. But diet, exercise, hormones, and many other things also change your temperature, so your body is constantly making adjustments to keep up.
When you are too hot, your body tries to radiate, or get rid of heat, by widening your blood vessels to carry excess heat to your skin’s surface. As sweat evaporates off your skin and blood loses heat to the air, your body cools. When you’re too cold, your body tries to insulate, or trap heat by narrowing your skin blood vessels so the blood keeps more heat in your core, as well as raising your temperature through shivering.
Imbalances in your temperature reflect the challenges your body is facing each day. Your temperature is an indicator of how you’re recovering, how prepared you are for the day, if you’re coming down with an illness, or if hormones in your body are hard at work.
On average, the human body ranges from 36.5–37.5 °C (97.7–99.5 °F). Your body temperature doesn’t remain constant; however, it fluctuates throughout the day—following your circadian rhythm. Generally, this means your temperature is lowest a couple hours before you wake up and highest when you’ve woken up, and again an hour or two before you get sleepy.
An individual’s core body temperature typically changes by about 1 °C (1.8 °F) between its highest and lowest points each day. Anything outside of that range indicates that something is challenging your body and preventing it from adjusting.
At the surface of your skin, where heat from your blood and chill from the environment are more intermingled, the range is typically a bit bigger.
Your skin temperature and core temperature can even change in opposite directions. For example, if your core is too hot, your body tries to cool itself by pushing blood to the skin so it can dump that excess heat into the environment. But in the case of fever, or after ovulation, both will rise in a similar manner. So keep in mind that where you measure from matters when making comparisons.
During the day, your temperature varies as you move, eat, drink, socialize, and change your environment. Because there is so much variation in temperature throughout the day, if you want to measure your overall health status, it’s best to measure your temperature at night when your body is in a consistent state.
At night, your body’s temperature is a reflection of what happened during the day – is your body stressed outside of its ideal range or is it able to fluctuate normally?
Your body temperature is highly individual and may change over time. It’s best to compare your temperature to your own baseline and avoid comparisons to those around you.
Watch for these patterns in your nightly temperature:
Your circadian rhythm helps your body move between being awake or asleep. As part of this rhythm, your core body temperature drops near your optimal bedtime and rises again just before you wake up. If your average temperature is significantly higher or lower than normal, or if it fails to change when you try to go to sleep, then your body may be ‘stuck’ under strain—preventing it from flexibly adjusting throughout the night.
If you’re getting sick, even before you get a fever, your body’s temperature may rise. While estimates vary, normal daily temperature fluctuation is around 1 °C (1.8 °F). If you spot a high temperature outside of that range, it may mean your body is fighting to keep you healthy. Some illnesses may even cause your body to start a fever. Regardless, a positive sign of recovery is your temperature returning to normal afterward.
Powering your organs can generate a lot of internal heat. If you have a large meal or a few drinks close to bed, you may find that your temperature remains elevated throughout the night, as your digestive system is hard at work. Being in touch with your body can help you identify if overheating is due to something you can control (like mealtimes or bedding) or is the result of another bodily change such as hot flashes.
If you track your menstrual cycle, you may see your ideal temperature range shift with your hormone cycle. This usually results in lower body temperature readings during the first half of the menstrual cycle (follicular phase), followed by a rise during the second half (luteal phase). Note that using hormonal birth control may suppress monthly temperature variation.
Your body does a great job of maintaining your ideal temperature, but there are ways you can influence it to your advantage.
You have the power to influence your temperature more than you might think. There are even Tibetan monks who meditate and raise their core body temperature high enough to dry a wet towel resting on their backs—but try starting with one of these simple hacks:
Observing your body’s day-to-day temperature can bring you insights, so start monitoring your body’s trends and see what patterns emerge.