Internal tremors refer to the unsettling sensation of inner shaking, vibration, or buzzing that occurs without any visible external movement. This subjective feeling, often described as an internal quivering in the chest, abdomen, or limbs, can be confusing, especially when felt upon waking. This article explores the common physiological mechanisms and systemic factors that contribute to internal tremors timed with the transition from sleep to wakefulness.
Understanding the Sensation
An internal tremor is a sensory perception of shaking that originates within the body, differentiating it from an external tremor involving rhythmic, observable muscle contractions. People often describe the experience as feeling like a cell phone vibrating inside their body or a low-frequency buzzing sensation. The lack of visible physical movement makes this subjective symptom difficult to describe, yet the feeling is real and often intense.
Neurologically, internal tremors are believed to stem from the same underlying causes as visible tremors. The resulting physical movement is simply too subtle to be detected by the human eye. The sensation may be linked to motor neurons firing at a frequency strong enough to create a sensory feeling of vibration, but not powerful enough to recruit the muscle fibers required for motion.
Causes Linked to Sleep Transitions
The timing of the tremor upon waking frequently points to physiological processes related to the body’s abrupt shift from sleep to an active state. These acute causes are tied directly to sudden changes in hormonal and systemic balance during the sleep-wake cycle. The body’s autonomic nervous system, which controls involuntary functions, often struggles momentarily to synchronize during this transition.
A significant factor is the body’s hormonal response to waking, known as the Cortisol Awakening Response (CAR). Cortisol and adrenaline levels naturally spike in the first 30 minutes after waking to prepare the body for the day ahead. If an individual has a hypersensitive nervous system, this natural chemical surge can cause an immediate sensation of internal shaking or jitteriness.
Low blood sugar, or hypoglycemia, can also trigger this effect overnight or in the early morning hours. When glucose levels drop below normal, the body releases stress hormones like epinephrine and norepinephrine to mobilize stored sugar for fuel. This hormonal release directly causes physical symptoms, including the feeling of being shaky or tremulous upon waking. Having a balanced dinner and a small, complex-carbohydrate snack before bed can sometimes help stabilize blood glucose levels throughout the night.
Underlying Medical and Lifestyle Factors
Chronic systemic issues can make an individual more susceptible to internal tremors, which are often exacerbated upon waking. Chronic anxiety and sustained stress are major contributors, as they maintain a state of hyper-vigilance in the nervous system. The continuous high baseline of stress hormones sensitizes the nervous system, making it more reactive to the natural morning cortisol spike.
Thyroid Dysfunction
Thyroid dysfunction, particularly hyperthyroidism, is a systemic condition known to cause tremors. An overactive thyroid gland produces excessive amounts of thyroid hormones (T3 and T4), accelerating the body’s entire metabolic rate. This hormonal excess enhances the excitability of nerve cells and increases sensitivity to adrenergic hormones, resulting in fine tremors often felt internally.
Medication and Withdrawal
Medication side effects are a common cause of internal shaking. Certain classes of prescription drugs can increase nervous system activity, thereby inducing or worsening tremors. Examples include some asthma medications like albuterol, specific antidepressants such as selective serotonin reuptake inhibitors (SSRIs), and mood stabilizers. Withdrawal from substances like high levels of caffeine, nicotine, or alcohol can also lead to significant internal trembling, especially after the body has processed the substance overnight.
When to Consult a Healthcare Professional
Although internal tremors are often linked to benign causes like anxiety or temporary blood sugar fluctuations, they should be evaluated by a healthcare professional if they are persistent or accompanied by other symptoms. It is advisable to seek medical attention if the internal shaking occurs daily, begins to worsen over time, or starts to interfere with daily function. A doctor’s visit is also warranted if the tremor is accompanied by visible physical shaking, which indicates a progression of the symptom.
A medical evaluation can effectively rule out systemic causes like thyroid disease or medication interactions, which are often easily managed once identified. Concerning accompanying symptoms include unexplained weight changes, a rapid or irregular heartbeat, or problems with coordination and balance. Keeping a detailed log of when the tremors occur, what they feel like, and any recent changes in diet or medication can significantly assist a physician in accurately diagnosing the underlying issue.