Many of us struggle to leave out beds in winter and research shows that it's not laziness which keeps us under the duvet. While humans don't hibernate, researchers from St. Hedwig Hospital's Clinic of Sleep & Chronomedicine in Berlin found that we may need more sleep during the colder months of the year. Prof Andrew Coogan from the Department of Psychology at Maynooth University joined Drivetime on RTÉ Radio 1 to discuss the findings. (This piece includes excerpts from the conversation which have been edited for length and clarity - you can hear the discussion in full above).
Not only did the research find that patients sleep longer in winter, but the type of sleep was actually different too, explains Coogan. "Patients had more what we term REM sleep, the phase of sleep during which we dream. The second half of the night tends to be richer in REM sleep and our first half of the night seems to be richer in non-REM sleep. What this study is showing is not only do we sleep longer in the winter, which we suspected anyway, but actually the type of sleep we have changes across the season so we have more of this non-REM sleep."
However, it's not apparent from the study why this is the case, though it may be related to daylight and darkness. "We know our brain function is affected by both how bright the light is outside and how long we have natural sunlight in particular and obviously we have a lot shorter days in winter."
So how do people deal with this need for more sleep if they're still getting up at the same time? "Bedtime is the one thing that we can move earlier", says Coogan. "If you have to get up to go to work or school, you've got to get up at a fixed time. Usually our wake time is when we'd love to lie in, but it's unfortunately not an option for most of us most days."
An early bedtime, though, would be useful in another way. "The first half of the night, non-REM sleep, is really our restorative sleep and it allows our body to catch up with itself. We think that REM sleep in the second half of the night is probably particularly important for emotional health. We refill our energy stores in the first half of the night, but the second-half of the night is probably more about the brain really processing what's going on and is really important for our sort of psychological well-being."
The one thing to bear in mind is that we do need good, quality sleep. "Lack of sleep and poor quality sleep is associated with lower moods, irritation and poor cognition. We're generally grumpier and slightly more unhappy then than if we get enough sleep. We become more impulsive if we don't get sufficient sleep and we make poor food choices and go for the sugary, fatty stuff that we know we shouldn't have."
