8.3 Hormones That Impact Sleep

Melatonin

Melatonin is a hormone produced in the pineal gland of the brain. It is present in our bodies in low levels during waking hours and levels start to increase a few hours before bedtime, reaching its peak while we sleep. Light and its influence on melatonin dictate our circadian rhythm; exposure to light suppresses the release of melatonin from our pineal gland. Short-wavelength light-—blue and green light—appears to have more significant effects on decreasing melatonin levels (Wright & Lack, 2001; Chang et al., 2015), whereas red light does not suppress melatonin to the same extent (Zeitzer et al., 1997). Knowing this, you can attempt to control what kind of light you’re exposed to at different times based on whether you need to be sleeping or staying awake. Taking steps to adjust light-exposure or talking to a trusted healthcare professional about melatonin supplements can help address problems one might have with sleep onset.

Cortisol

Cortisol is a hormone produced within the adrenal gland in low levels throughout each day and higher levels in response to stress. Like many other hormones, including melatonin, cortisol also follows a circadian rhythm. Cortisol tends to be present in its lowest amounts around midnight and highest around 8:30 in the morning (Debono et al., 2009). In essence, melatonin and cortisol are on opposing schedules. Excess cortisol has been linked to insomnia, sleep disturbances, and mood concerns that can disrupt sleep (Son et al., 2011) and stress is associated with sleep disorders and sleep disruption (Kahn et al., 2013; Germain et al., 2003). Cortisol levels can be dysregulated by a disease—as in the case of Cushing’s Syndrome where one’s body produces too much cortisol—but is also influenced by everyday and chronic stress. Taking steps to prevent or address stressors is one possible way to reduce the negative impact of cortisol on sleep.

Sex Hormones

Sex hormones and changes or cycles associated with menstruation, puberty, pregnancy, and menopause can impact sleep. Many people who menstruate report poorer sleep during the week before and during the first several days of menstruation (Sharkey et al., 2014). Pregnancy, menopause, and postmenopause can also result in insomnia, poor sleep quality, and changes in body temperature that disturb sleep (Wilson et al., Barnes et al., 2011; Mong et al., 2011). Taking oral contraceptives can also impact sleep; those who take them don’t generally notice subjective changes in their sleep quality, but research has shown that people taking oral contraceptives have slightly higher melatonin levels, a slightly higher body temperature, and spend more time in Stage 2 or REM sleep (Baker & Driver, 2007; Baker, Mitchell, & Driver, 2001).