Stolen sheets, snoring and hot flashes are just some of the annoyances that lead a quarter of U.S. couples to sleep apart, according to the National Sleep Foundation. But do the benefits of sharing a bed outweigh such costs? One neurologist, Rachel E. Salas, the assistant medical director for the Johns Hopkins Center for Sleep, shares her expert opinion.
snoring：打鼾，打呼噜 annoyance：烦恼，可烦之事
Safety, Warmth
People have slept in the same bed as a family unit for millennia-mainly for warmth and protection from predators and outsiders, says Dr. Salas, who has studied the history of sleep.
millennia：几千年，太平盛世
'Back in the cave days and even through recent history, many people didn't bathe often or have lots of clothes, so they slept naked. Sleeping together was essential for warmth,' she says.
Then as now, she says, it is human to feel safer knowing someone is lying close beside you.
The Science of Spooning
There have been few scientific studies on couples sleeping together. But experts say oxytocin, the so-called love hormone, is released during many types of touching, including cuddling. Increased oxytocin helps the body relax, reduces blood pressure and promotes healing, Dr. Salas says. It also results in emotional feelings related to affection, security and love.
spooning：搂抱 oxytocin：催产素 cuddling：拥抱，搂抱
A recent study showed a link between quality of sleep and couples' daytime interactions. For men, the better the sleep a couple got, the smoother their next-day spousal interactions, Dr. Salas says. For women, less negative interaction with their husbands during the day led to more restful sleep that night.
spousal：结婚的
'I can't quote any studies, but from my neurology background, I would suspect that having a person that you are the protector for or who protects you nearby increases the release of neurotransmitters involved with good sleep,' Dr. Salas says.
neurotransmitters：神经传导物质
Wake-Up Calls
Getting quality sleep enhances a person's quality of life, Dr. Salas says. People with sleep disorders, such as apnea, night terrors or sleepwalking, may benefit from having a bed partner who can observe nighttime behaviors and help with a diagnosis.
apnea：窒息，呼吸暂停 night terror：惊梦
But for some people, sleeping together could do more harm than good: 'If you wake up often from ambient noises or get hot in your sleep, keeping your bed to yourself may be exactly what you need.'
ambient：周围的，环绕的，外界的
'Humans are Social Creatures'
Sleeping apart is a relatively modern phenomenon and varies across cultures, Dr. Salas says. 'My father is from Mexico and my mom is from Texas, and both of them slept with all of their brothers and sisters when they were growing up,' she says. If you go to other countries, whole families still sleep together, she says. 'Humans are social creatures. We want someone nearby.