There is an interesting article in the November edition of the Sleep Journal about the relationship between loneliness and sleep. The study authors describe a previous study that showed that loneliness was associated with more frequent awakenings, but not with the total duration of sleep. The authors feel this makes sense from an evolutionary perspective, as humans may wake up more frequently to ensure safety if sleeping alone.
The study participants were Hutterites, a communal group from South Dakota that sound similar to the Amish. They chose this group because they may be among the most socially connected group in the United States. Eligible participants were at least 19 years old. The study authors recorded the participants' subjective reports of loneliness, depression, anxiety, stress, sleep quality, and daytime sleepiness. Actual sleep duration and number of awakenings was measured for 7 continuous days via a home sleep study device called an actigraph. Actigraphy does not actually measure sleep, but it is a good correlate to an actual sleep study done in a sleep lab. Also, actigraphy can not rule out sleep-fragmenting disorders like sleep apnea or periodic leg movements.
The results showed that perceived loneliness was associated with more awakenings at night as measured by the actigraph. Interestingly, loneliness was not correlated with subjective increase in awakenings or sleep duration, and it was not significantly associated with actigraph-derived sleep duration. The effect of loneliness persisted even when controlling for negative affect (depression). Also, loneliness was not associated with increase report of subjective daytime sleepiness.
The authors point out that the results do not determine if loneliness causes worse sleep or if worse sleep contributes to loneliness. It could be that multiple awakenings lead to more loneliness, rather than the other direction. This is because depressive feelings were not associated with sleep fragmentation. Also, it is the perception of loneliness that is associated with sleep fragmentation, rather than marital status and number of family members the participants reported. This means that even if someone was married and had plenty of social relationships, they would still have more fragmented sleep if they felt lonely.