BURROWING under the bedclothes may be the most sensible way to cope with dark winter mornings, according to researchers from the National Institute of Mental Health, Bethesda, Maryland. They suggest in New Scientist that staying in bed for 14 hours a night during the winter months, interspersing sleep with meditation-like periods of 'quiet wakefulness', may result in fewer health problems. Artificial lighting, they argue, has disrupted natural sleep patterns, leading to widespread sleep deprivation.