After our descent into the darkest time of year, we now celebrate different festivals of lights. Festivals track the passing of time and include rituals focusing on our own relationship to our changing environment. The dance between seasonal shifts of darkness and light is mirrored in the rhythmic shifts in our own bodies. We have our own circadian clock which works to help us stay in tempo with our surroundings.
Our bodies work from the impulse to maintain equilibrium, or in physiological terms, homeostasis; this is choreographed by our brain’s continuously adjusted hormone releases. At times, these can rise and fall with the smooth sway of a waltz while at others we experience more erratic, less graceful physical progressions.
So, what is it that makes our internal metronome? What makes us tick? Today, we’re talking about core body temperature and how it interacts with and influences our own internal clock.
During the day, your body runs warmer by a few degrees, helping you feel alert. As night falls, physiological changes occur, lowering your core body temperature by dilating blood vessels in your skin which facilitates a faster release of heat. This change in your internal climate helps to affect a slowing calmness. Ideally, at this time you take some needed respite from your day and sink gently into the still of sleep.
When you reach the REM (Rapid Eye Movement) stage of sleep, the temperature regulating cells in your brain switch off and your body temperature is more directly influenced by the ambient temperature of the room or space surrounding you. This phase of REM sleep is a critical time of restoration and rejuvenation. As your core temperature drops, particular hormones are released which send signals to your immune system to repair particular tissues and areas of distress; this is also the phase of sleep within which you process memories and emotions that you may not have fully attended to or taken in during the day. This shift all takes place with as little as a single degree of temperature change from your average daily core temperature. As night gives way to day, your body temperature begins to rise once again, commencing of series of events which cause you to emerge from sleep and wake into the new day.
So your body temperature helps determine when you fall asleep and the cooler your thermostatic setting (within reason), the sounder your sleep.
Sleep efficiency is a measurement of sleep quality and is based on the amount of time you spend in bed compared to the amount of time you are actually sleeping. A sleep score of 60% means that, of the total time you spend in bed, you are actually sleeping for 60%. Ideally, you will work towards an average sleep efficiency of 85% or higher.
There are a number of different types of insomnia with various causes. As many women know, menstrual irregularities, such as those produced by perimenopause or menopause, are often accompanied by heightened body temperature during our sleep hours. Not only can these hot flashes and sweaty agitations leave us feeling unattractive but they can also deprive us of our nightly renewal.
Next week I’ll share why this occurs and what to do about it, but in the meantime, please consider a few suggestions to help solidify or re-establish your sleep routine:
- Try soaking in the tob an hour or two before your slip into slumber. Taking a bath warms your body but, as you emerge from the warmth and the water evaporates from your skin, your body goes into cool down mode which is sympathetic to the bed time effect you’re looking for.
- Keep your bedroom between 60-67 degrees Fahrenheit.
- Avoid synthetic pj’s, bedding or mattresses. Natural fibers are more breathable and conducive to effective temperature regulation.
- Try to exercise in the morning or during the day — exercising in the evening can delay your body’s temperature reduction and keep you awake later.
In these days of maximum darkness, while we welcome back the light, I wish you the warmth of love the coolness of restorative sleep.
Please pass this along to anyone you know who is struggling with their hibernation habits. Next week, we’ll dive deeper into how fluctuating hormonal tides ruffle our capacity to sleep.