We spend nearly a third of our lives sleeping, yet the reasons why we need sleep are still poorly understood. What we do know that the brain is highly active during sleep. According to a popular current theory, the resting brain is nearly as busy as the waking brain because during sleep, neural circuits replay memories in order to aid learning by strengthening the circuits. But researchers are now presenting a very different explanation for this activity.


"Every night, while we lie asleep, blind, dumb and almost paralyzed, our brains are hard at work. Neurons in the sleeping brain fire nearly as often as they do in a waking state, and they consume almost as much energy," researchers Giulio Tononi and Chiara Cirelli of the University of Wisconsin–Madison write in a new Scientific American feature[1] . "What is the point of this unceasing activity at a time when we are supposedly resting? Why does the conscious mind disconnect so completely from the external environment while the brain keeps nattering on?"


The answer they propose in a new hypothesis is, essentially, that the brain's activity during sleep weakens the brain's neural connections, rather than strengthening them, as has generally been thought. Their reasoning is that strengthening the neural connections would saturate the brain's circuitry, consuming so much energy that the brain would struggle to encode new information. The purpose of sleep, they argue, is to bring brain cells back down to their baseline.


Check out the video below to see Tononi discuss his research in a talk presented at an Allen Institute for Brain Science symposium[2] , and click here for more of the latest sleep research[3] .




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  • Easy Forward Bend (variation of Sukhasana)


    The easy forward bend pose is accessible even to beginners, and it's a great one to try before bedtime. If you're tight in the hips, Bielkus advises sitting on top of a pillow to make the pose a bit more relaxing. "This one is good for sleep," says Bielkus. "It also eases tension and lets the hips open up, and just creates an overall sense of ease in the body."




  • Standing Forward Bend (Uttanasana)


    To perform this pose, stand with the feet about six inches apart and fold the torso to the ground, reaching toward the ground or bending the arms and grabbing opposite hand to opposite elbow. In addition to helping to relieve headaches and insomnia, the pose can also be helpful for lowering stress levels, <a href="http://www.yogajournal.com/poses/478" target="_blank">according to Yoga Journal</a>. "Sway a little side to side and breathe," says Bielkus. "Bend the knees as much as needed to ease any strain. Tension in the legs and hips will start to release."




  • Child's Pose (Balasana)


    The quintessential resting pose in many yoga classes, child's pose helps to calm the mind and relieve tension in the body. Fold the torso over the legs with the arms extended or by the sides, and rest the forehead on the ground. "Take long deep breaths," Bielkus suggests. "Massage the forehead left to right easing tension at the brow point."




  • Plow Pose (Halasana)


    Yoga Journal <a href="http://www.yogajournal.com/poses/479" target="_blank">recommends </a>staying in the plow pose for one to five minutes to fall asleep easier. Lie down on your back, lifting your legs over your head and then to the ground behind you, with your hands either on your back for support or on the floor. "By turning the flow of blood around, you bring new vitality into the body," says Bielkus.




  • Legs Up The Wall Pose (Viparita Karani)


    This simple pose, performed against a wall, is excellent for evening relaxation and stress relief. Bielkus recommends staying in the pose for as long as five minutes, with the eyes closed and using a soothing eye pillow if desired. "When we flip the legs up, the blood can rush back down to the heart," says Bielkus. "It has a soothing quality."




  • Corpse Pose (Savasana)


    Get your body into sleep mode with a simple corpse pose, focusing the attention on the body and breath, and letting go of the day's worries. "By focusing the mind and bringing awareness in, you take the mind off of what is causing stress or restlessness," says Bielkus.




  • Supine Spinal Twist (Supta Matsyendrasana)


    This reclining twisted pose can easily be performed in bed before you fall asleep. Lie down on your back and bring the right knee into your chest and then across your left side. Extend the right arm out and gaze to the right, taking several deep breaths and then repeating on the other side. You can also try bringing both legs up and then over to each side, as pictured at left. "Gentle twists relieve tension throughout the whole spine and also aid in digestion and help us rinse out some tension from the day," Bielkus says.




  • Seated Spinal Twist (Ardha Matsyendrasana)


    Like the supine twist, the seated spinal twist (also known as the half lord of the fishes pose) can create a sense of relaxation in the body while gently stretching the spine. The stretch can be practiced with both legs bent or with one outstretched.




  • Reclining Butterfly (Supta Baddha Konasana)


    A variation of the basic butterfly pose (pictured at left), the reclining butterfly can help the body get into rest mode. Lie down on your back -- on your bed or on a mat -- and bring the feet together, splaying out the knees in a diamond. If your hips are tight and the pose feels too intense, Bielkus suggests putting a folded blanket or cushion under each of the knees. "Bring one hand to your heart and one hand to your belly," Bielkus says. "Breathe deeply observing the breath move in and out of the body."




  • Left Nostril Breathing (Surya Bhedana)


    To try this relaxing breathing exercise (<em>pranayama</em>), you can either sit up crossed-legged or lie down on your right side. Cover the right nostril with your thumb and extend the fingers out. Then take five to 10 deep breathes out of your left nostril. "If I can't sleep ... As soon as I've done three left nostril breaths, I'm out," says Bielkus. "It's really, really effective."