There are many reasons why we can feel tired in wintertime. The long nights, short days and cold temperatures during winter can make many people feel tired and sluggish, and perhaps even want to hibernate. But why does the season impact energy levels? "The arrival of winter brings with it a number of potential challenges for sleep, including reduced exposure to sunlight, cooler temperatures, clock changes, and lowered immunity," said Guy Meadows, a sleep researcher and co-founder of The Sleep School (opens in new tab), an online platform offering science-based support around sleep. "All these [factors] disturb sleep, making it harder to get up in the morning." Hormonal changes, unhealthy behaviors and certain vitamin deficiencies can also be behind the onset of seasonal fatigue. For some people, however, the onset of winter can result in more than a feeling of blahness. For some, excessive tiredness, grogginess, lack of energy and low mood are symptoms of a disorder known as seasonal affective disorder (SAD). Below, we take a closer look at some of the most common causes of seasonal fatigue. Seasonal affective disorder SAD is a type of depression that occurs when the days get shorter in winter. According to the National Institute of Mental Health (opens in new tab) (NIMH), symptoms often start in the late fall or early winter and go away during the spring or summer. Many symptoms of SAD are psychological, such as low mood, loss of interest in activities and feelings of hopelessness. There can also be physical symptoms, such as low energy, sleep problems or appetite changes, feeling sluggish and lethargic, having low energy, experiencing sleep problems and experiencing appetite or weight changes. The NIMH (opens in new tab) notes that SAD is more common in women than men and tends to affect people who live further north, where winter days are shorter. If you think you may have SAD, speak to your doctor, who will be able to devise an appropriate treatment plan. Hormones Hormones can affect energy levels. serotonin, a hormone often tied to mood, and melatonin, a hormone that regulates sleep, maintain the body's circadian clock — its internal clock — which fluctuates with the seasonal night-day cycle. The brain's pineal gland is responsible for producing melatonin, which it does in response to darkness. However, because the winter months are often darker and have fewer hours of sunlight, this can alter melatonin production, making us produce more of the hormone in the morning (when it is still dark) and earlier in the evening. According to the Mayo Clinic (opens in new tab), fluctuating levels of the hormone can play a role in developing SAD by altering sleep patterns and mood. According to Meadows, being exposed to light immediately after waking up can help reduce the amount of daytime melatonin production. "When you expose yourself to natural or artificial light as soon as you wake up, the effects can be transformative," he said. "Having a regular ‘wind-up’ routine can help to entrain the brain to associate that time in the morning with being awake, helping to boost morning alertness and energy and reduce feelings of grogginess." Source
