Sleep is the cornerstone of health, deeply influenced by the interaction between hormones and circadian rhythms, says Dr Yatin Sagvekar, a neurologist at Kokilaben Dhirubhai Ambani Hospital, Navi Mumbai, India.
One of the most important hormones is cortisol, also known as the stress hormone, but in many cases its role in sleep is not fully appreciated.
Cortisol is secreted by the adrenal glands and follows a 24-hour cycle, synchronized with the body's circadian rhythm. It helps regulate wakefulness and the transition to a state of rest.
However, when this rhythm is disrupted by stress, unhealthy lifestyle or sleep disorders, it will seriously affect our physical and mental health.
Dr. Yatin Sagvekar emphasized that cortisol plays an important role in maintaining circadian rhythms, directly affecting sleep and wake cycles.
Cortisol and the 24-hour cycle
Cortisol peaks around 8 a.m., helping your body wake up and prepare for the day. It starts to rise in the second half of sleep, stimulating alertness when you wake up.
Throughout the day, cortisol levels gradually decrease and reach their lowest point near midnight, when the body needs to rest.
The stability of this cycle is important for quality sleep, notes Dr. Sagvekar. Any disruption, such as stress or lifestyle changes, can reduce sleep quality.
The HPA axis and its impact on sleep
Cortisol is regulated by the hypothalamic-pituitary-adrenal (HPA) axis. At night, the HPA axis is less active in preparation for sleep. However, when the HPA axis is disrupted, such as by chronic stress, sleep disorders such as sleep apnea, or unhealthy sleep habits, it can negatively affect sleep quality.
HPA axis dysfunction and insomnia
When the HPA axis is overactive, it can cause chronic insomnia, disrupting sleep and prolonging non-restorative rest.
Lack of sleep leads to higher cortisol levels, which not only impairs sleep structure but also causes other serious health problems.
Cortisol, insomnia and health problems
Dr. Sagvekar also said that chronic sleep loss and overactivity of the HPA axis may be linked to diseases such as obesity and type 2 diabetes.
Elevated cortisol levels can disrupt glucose metabolism and reduce insulin sensitivity, contributing to the development of these diseases. In addition, the immunosuppressive effects of cortisol increase the risk of infection.
