The idea that sleeping on your back can increase your height is a popular misconception. There is no scientific evidence that changing your sleep posture, even to the supine position, results in a permanent increase in physical height. Growth refers to the irreversible lengthening of the bones, a process entirely separate from how you position your body during sleep. While sleep is important for growth, the specific position does not determine your final adult height. The belief likely stems from temporary changes in spinal length that occur overnight.
What Really Determines Human Height
Final human height is a complex trait primarily dictated by genetics, with 60 to 80 percent of a person’s potential stature inherited from their parents. Height is considered a polygenic trait, meaning it is influenced by the cumulative effects of variations in hundreds of different genes. These genes regulate the processes of bone development and the activity of growth plates.
The actual mechanism of lengthening occurs at the growth plates, or epiphyses, which are areas of cartilage near the ends of long bones. Cells within these plates divide and eventually turn into solid bone tissue, continuing throughout childhood and adolescence. Growth stops when these plates fully fuse with the main part of the bone, typically in late adolescence or early adulthood.
Hormones serve as the chemical messengers that orchestrate this complex process. Human Growth Hormone (HGH), produced by the pituitary gland, stimulates the liver to release Insulin-like Growth Factors (IGFs), which directly promote growth plate activity. While HGH secretion is highest during deep sleep, this hormone release is a function of the sleep cycle itself and is not dependent on lying on your back. Environmental factors like childhood nutrition and overall health account for the remaining influence on final height.
How Sleep Posture Affects Spinal Alignment
The body’s length changes slightly throughout the day due to the compression of the intervertebral discs, the fluid-filled cushions between the spinal bones. During waking hours, gravity and daily activities squeeze fluid from these discs, resulting in a slight decrease in height by the evening. When a person lies down to sleep, the spine is relieved of this vertical pressure.
The lack of gravitational load allows the intervertebral discs to rehydrate and expand, a process known as spinal decompression. This expansion is why most people measure slightly taller in the morning compared to before bed, but this temporary length gain reverses once standing upright. Sleeping on the back is often recommended because it promotes a neutral spine, maintaining the natural curves of the neck and lower back without strain.
The supine position allows for the most even distribution of body weight, reducing pressure points that can lead to pain or stiffness upon waking. To support the natural lumbar curve while on the back, placing a small pillow beneath the knees is often suggested. This optimal alignment is about spinal health and comfort, not adding permanent bone length.
Age-Specific Recommendations for Sleep Position
Recommendations for the safest and most comfortable sleep position change depending on a person’s age and health status. For infants, the American Academy of Pediatrics strongly advises they be placed on their backs for all sleep times until they reach one year of age. This supine position has been shown to reduce the risk of Sudden Infant Death Syndrome (SIDS).
For older children and adults, the best position is the one that allows for the most restful sleep while maintaining the spine’s neutral alignment. Sleeping on the back is a preferred option for spinal health, but side sleeping is also common and beneficial when a pillow is placed between the knees to keep the hips aligned. Individuals with conditions such as obstructive sleep apnea or acid reflux may find side sleeping or sleeping with the upper body slightly elevated to be more helpful. Stomach sleeping is discouraged for all ages due to the strain it places on the neck and the flattening of the natural lower back curve.