As I write this post the Kickstarter campaign for Gravity: The Weighted Blanket is coming to a close.
I really hate when companies use research to make egregious claims then rip-off customers. So I’m going to break down the section labeled “The Science” from Gravity’s Kickstarter page to see if their claims stack up to the evidence they provide.
Claim 1: “Though weighted blankets have been used in the medical community for many years now, the measurable health benefits have only recently begun to emerge in scientific studies. So far, the findings have been incredible.”
The studies they cite (see below) agree with this statement completely, and weighted blankets have been shown to help numerous people with mental health issues or chronic insomnia.
Claim 2: “Gravity uses the power of proprioceptive input (more commonly known as “deep touch pressure stimulation”), a well-regarded therapeutic method that stimulates pressure points on the body linked to improved sleep, mood, and relaxation.”
Let’s re-define proprioceptive input according to Blanche et al. 2013: “The sum of neuronal inputs from the joint capsules, ligaments, muscles, tendons, and skin, is a multifaceted system that affects motor control and is hypothesized to have an impact on behavior regulation (Ayres, 1972, 1989; Blanche & Schaaf, 2001; Dunn, 1999, 2001; Mukhopadhyay, 2003) and motor control (Ayres, 1972, 1989; Lephart & Fu, 2000).” As you can read, it’s hypothesized to impact behavior regulation. However, this seems like a fair statement overall.
Claim 3: “A reduction in cortisol levels and an increase in serotonin production, which decreases heart rate and blood pressure.”
I don’t know about this one. There was no data on biochemical markers such as cortisol or serotonin in the studies linked on their page. I also couldn’t find any other data confirming this in a quick Pubmed search. I could have missed it, but I doubt it exists in a normal population. There is data (see study #4 below) indicating a 30lb weighted blanket can reduce HR and BP in a 5-minute anxiety test and marginally decrease heart rate and blood pressure – though that may not translate to a physiological difference.
Let’s take a look at the evidence they cite:
Population: Inpatient psychiatric unit
Method: Rating systems
Discussion: “Previous literature supports the utility of weighted items for calming and grounding children (9) and our study provides initial evidence for the effectiveness of weighted blankets in the adult psychiatric inpatient population. Even where a sensory room is not available, these results would suggest that weighted blankets may be a useful resource to assist consumers to self-manage distress. Rocking motions have also been reported to be effective for soothing older persons with dementia10 and, although not significant, trends emerging from our small sample (21 occasions of rocking chair use) indicate further investigation of this self-soothing resource is warranted.”
Conclusion – “Use of the sensory room appears to be valuable in the attenuation of distress and behavioral disturbance. Results also support the usefulness of weighted blankets in inpatient psychiatric settings.”
Limitation – “The primary limitation of this study is that raters were not blinded. It is likely that at least some of the improvements noted are related to raters’ expectation that there should be positive effects.”
Take Home: I’m not sure the use of a sensory room full of items to help reduce anxiety translates to everyday usage for a normal population. Furthermore, how do we know it wasn’t a combination of the items causing the effect? The data from table 2 did not add to 100% which indicates the subjects could have used more than one item provided. (and probably did).
Study #2: Design of Haptic Interfaces for Therapy
Intro: “Weighted blankets and vests have been used for years to prevent crisis states with children, adolescents, adults and the elderly. Heavy blankets and vests can actually prevent these panic attacks and allow children and adults to resume normal activities . Recently, similar kinds of touch therapy have been shown to be effective at comforting patients and reducing violence. With the exception of medication, few psychotherapy alternatives exist outside a care-giving facility. We are building the first generation of computerized touch therapy devices to assist therapy with the potential to transform the way touch therapy is conducted in care-giving facilities.”
What did this study do? It evaluated the use of prototypes by a panel of medical experts. Basically, it’s a pilot study to determine if any of these prototypes should be considered for clinical trials for mental health patients.
Best quote from the study: “Weighted blankets and vests have been used for years to prevent crisis states with autistic patients . When placed on an autistic child this type of distributed pressure can prevent a panic attack. “
Reference 10 from quote: Champagne, T., and Mullen, B. (2005) The Weighted Blanket: Use and Research in Psychiatry. MAOT 2005
Background: “The application of deep pressure, through for example weighted vests and blankets, has been reported to produce a calming and relaxing effect in clinical conditions such as autism spectrum disorders (ASD), attention-deficit hyperactivity disorder, and pervasive developmental disorders [8-15]. Applying deep pressure has been shown to be beneficial for children with high levels of anxiety or arousal  and deep pressure touch may also alleviate anxiety (e.g. in dental environments and bipolar disorder [17,18]). There are also anecdotal reports suggesting that the elderly who suffer from anxiety and dementia may find relief from deep pressure touch and many nursing homes are experimenting with weighted blankets. “
Study Population: 31 subjects (11 men, 20 women) between 20-66 who had issues of chronic insomnia, which was defined as difficulties in falling asleep and/or maintaining sleep for several nights a week (> 3 days) for more than 3 months.
Limitations: Lack of control group, study duration, some missing data, and the inability to provide a placebo weighted blanket.
Conclusion: “The weighted chain blanket used in the present study had a positive impact on sleep, both objectively and subjectively, where a number of physiological and behavioral measures were improved during weighted blanket use. When the participants used the weighted blanket, they had a calmer night’s sleep, with a decrease in movements. Subjectively, they believed that using the blanket provided them through increased tactile and proprioceptive inputs, may provide an innovative, non- pharmacological approach and complementary tool to improve sleep quality.
Funding conflict: Supported by a grant from Somna AB – which is reported in funding acknowledgements.
Take Home: Great study overall, but doesn’t support the claims made by the website. The data shows a very, very small increase in mean sleep time improved (7 minutes). This data was statistically significant, but would seven minutes make a difference physiologically in a normal person sleeping regularly? Probably not.
Study #4: Exploring the Safety and Therapeutic Effects of Deep Pressure Stimulation Using a Weighted Blanket
Population: 20 males and 14 females aged 18 – 58.
Weight range: 112 – 234 lbs
Blanket Weight: 30lbs
Design: concurrent, nested, mixed methods
Results & Discussion: “The results of this study demonstrate that the use of a 30 lb weighted blanket did not adversely influence pulse oximetry, pulse rate, or blood pressure. Further, using SC as an anxiety metric, 33% of the participants were found to exhibit a greater reduction in anxiety with the weighted blanket than without the blanket. Observations reveal that there appear to be differences in the results. The corresponding STAI-10 survey responses showed that 63% of the participants rated their anxiety lower with the use of the weighted blanket. Furthermore, according to the exit survey, 78% reported a lower anxiety after using the blanket than when not using the blanket. Thus, the results indicate that the use of the 30 lb weighted blanket has a calming influence for some adults.”
Limitations: Only a 5-minute time frame was used in the study, which cannot be extrapolated out to a full night of sleep. All participants used a 30lb blanket, so results may be different with weighted blankets comparatively.
Take Home: Overall, this was the best-designed study they link. It was completed in a healthy, normal population. However, the 5-minute time frame of the tests is a major limitation (see above). Also, there was no real physiological or statistical changes in HR or BP if you look at figure 3 from the study.
Will a gravity blanket do what it claims? Probably not. This is much more useful for a clinical population who suffers from insomnia or mental health disorders. If you suffer from a disease such as those mentioned in the studies above – it is definitely worth a try – simply because of the low risk, low price and convenience.